Kristopher1997
Kristopher1997

常用算法C++实现及STL常用API（留着刷题用） - 侵删

文章目录

    • 一 STL some demos
    • 二 图论算法
    • 三 STL API
      • 1 **string**
        • 1.1 基本
        • 1.2 Iterator
        • 1.3 Capacity
        • 1.4 Modifiers
        • 1.5 String operations
      • **2 stack**
      • **3 queue**
      • **4 priority_queue**
      • **5 set**
        • 5.1 member functions
        • 5.2 Iterator
        • 5.3 Modifier
        • 5.4 Observers
        • 5.5 Operations
      • **6 map**
        • 6.1 Member functions
        • 6.2 Iterators
        • 6.3 Modifiers
        • 6.4 Observers
        • 6.5 Operations
      • **7 vector**
        • 7.1 Modifiers
      • **8 list**
        • 8.1 Modifiers
        • 8.2 Operations
      • **9 cstdio**
      • **10 cstring**
        • 10.1 Copying
        • 10.2 Concatenation
        • 10.3 Comparison
        • 10.4 Searching

一 STL some demos

  1. sort
#include 
#include 
#include 
#include 

using namespace std;

struct Point {
    int x, y;
    Point() {}
    Point(int xx, int yy) { x = xx; y = yy; }
};

struct Mycomp {
    bool operator() (const Point& p1, const Point& p2)
    {
        bool flag = false;
        if (p1.x >= p2.x) { flag = true; }
        else if (p1.x == p2.x && p1.y >= p2.y) { flag = true; }

        return !flag;
    }
} mycomp;

bool myfunction(const Point& p1, const Point& p2)
{
    bool flag = false;
    if (p1.x >= p2.x) { flag = true; }
    else if (p1.x == p2.x && p1.y >= p2.y) { flag = true; }

    return flag;
}

ostream& operator<< (ostream& os, Point& p)
{
    os << p.x << " " << p.y << endl;
    return os;
}

int main()
{
    vector vs;
    vs.push_back(Point(7,4));
    vs.push_back(Point(4,4));
    vs.push_back(Point(5,3));
    vs.push_back(Point(5,2));
    vs.push_back(Point(8,2));
    vs.push_back(Point(1,5));
    vs.push_back(Point(2,4));
    vs.push_back(Point(3,2));
    vs.push_back(Point(3,4));

    sort(vs.begin(), vs.end(), mycomp);
    for (int i = 0; i < vs.size(); i++) {
        cout << vs[i] << endl;
    }

    cout << "-------------------------------" << endl;

    sort(vs.begin(), vs.end(), myfunction);
    for (int i = 0; i < vs.size(); i++) {
        cout << vs[i] << endl;
    }
}
  1. sort_2
#include 
#include 

using namespace std;

struct Point {
    int x, y;
    Point() {}
    Point(int xx, int yy) { x = xx; y = yy; }
};

class MyComp
{
public:
    bool operator() (const Point& p1, const Point& p2)
    {
        if (p1.x < p2.x) { return true; }
        else if (p1.x == p2.x && p1.y < p2.y) { return true; }
        return false;
    }
} mycomp;

bool myfunc(const Point& p1, const Point& p2)
{
    if (p1.x < p2.x) { return false; }
    else if (p1.x == p2.x && p1.y < p2.y) { return false; }
    return true;
}

ostream& operator<< (ostream& os, const Point& p)
{
    os << "(" << p.x << ", " << p.y << ")";
    return os;
}

int main()
{
    vector vps;
    vps.push_back(Point(5,4));
    vps.push_back(Point(7,3));
    vps.push_back(Point(7,1));
    vps.push_back(Point(3,4));
    vps.push_back(Point(2,0));
    vps.push_back(Point(6,4));
    vps.push_back(Point(3,4));
    vps.push_back(Point(2,7));
    vps.push_back(Point(1,2));
    sort(vps.begin(), vps.end(), myfunc);

    for (vector::iterator it = vps.begin(); it < vps.end(); it++) {
        cout << *it << endl;
    }

    return 0;
}
  1. map
#include 
#include 

using namespace std;

struct Point {
    int x, y;
    Point() {}
    Point(int xx, int yy) { x = xx; y = yy; }
    bool operator< (const Point& p) const
    {
        if (this->x < p.x) { return true; }
        else if (this->x == p.x && this->y < p.y) { return true; }
        return false;
    }
    /*
    bool operator== (const Point& p)
    {
        if (this->x == p.x && this->y == p.y) { return true; }
        return false;
    }
    */
};

bool mycomp(const Point& p1, const Point& p2)
{
    if (p1.x < p2.x) { return true; }
    else if (p1.x == p2.x && p1.y < p2.y) { return true; }
    return false;
}

ostream& operator<< (ostream& os, Point p)
{
    os << "(" << p.x << ", " << p.y << ")";
    return os;
}

int main()
{
    bool(*fn_pt)(const Point&, const Point&) = mycomp;

    map pi(fn_pt);
    pi.insert(make_pair(Point(1,1), 1));
    pi[Point(1,2)] = 2;
    pi.insert(make_pair(Point(3,4), 4));
    pi.insert(make_pair(Point(4,5), 3));
    pi.insert(make_pair(Point(2,1), 8));
    pi.insert(make_pair(Point(7,5), 9));
    pi.insert(make_pair(Point(7,4), 1));
    pi.insert(make_pair(Point(6,3), 1));

    cout << pi[Point(1,1)] << endl;
    cout << pi.size() << endl;

    for (map::iterator it = pi.begin(); it != pi.end(); it++) {
        cout << it->first << " " << it->second << endl;
    }

    return 0;
}
  1. set
#include 
#include 
#include 

using namespace std;

struct Point {
    int x, y;
    Point() {}
    Point(int xx, int yy) { x = xx; y = yy; }

    bool operator< (const Point& p) const
    {
        if (this->x < p.x) { return true; }
        else if (this->x == p.x && this->y < p.y) { return true; }
        return false;
    }
};

ostream& operator<<(ostream& os, const Point& p)
{
    os << "(" << p.x << ", " << p.y << ")";
    return os;
}

int main()
{
    set ps;
    ps.insert(Point(1,1));
    ps.insert(Point(3,4));
    ps.insert(Point(2,9));
    ps.insert(Point(3,6));

    cout << ps.size() << endl;
    for (set::iterator it = ps.begin(); it != ps.end(); it++) {
        cout << *it << endl;
    }
    cout << "-----------------------" << endl;

    map mpi;
    mpi[Point(9,1)] = 1;
    mpi[Point(4,5)] = 5;
    mpi[Point(6,3)] = 3;
    mpi[Point(6,1)] = 7;
    mpi[Point(2,7)] = 9;
    cout << mpi.size() << endl;
    for (map::iterator it = mpi.begin(); it != mpi.end(); it++) {
        cout << it->first << " : " << it->second << endl;
    }

    return 0;
}
  1. priority_queue
#include 
#include 
#include 

using namespace std;

struct Point {
    int x, y;
    Point() {}
    Point(int xx, int yy) { x = xx; y = yy; }

    /*
    bool operator< (const Point& p)
    {
        if (this->x < p.x) { return true; }
        else if (this->x == p.x && this->y < p.y) { return true; }
        return false;
    }
    */
};

class Mycomp
{
public:
    bool operator() (const Point& p1, const Point& p2) const
    {
        if (p1.x < p2.x) { return true; }
        else if (p1.x == p2.x && p1.y < p2.y) { return true; }
        return false;
    }
};

ostream& operator<< (ostream& os, const Point& p)
{
    os << "(" << p.x << ", " << p.y << ")";
    return os;
}

int main()
{
    priority_queue, Mycomp> ppq;
    ppq.push(Point(7, 2));
    ppq.push(Point(4, 1));
    ppq.push(Point(3, 5));
    ppq.push(Point(8, 1));
    ppq.push(Point(2, 1));
    ppq.push(Point(3, 3));

    while (!ppq.empty()) {
        cout << ppq.top() << endl;
        ppq.pop();
    }

    /*
    priority_queue, greater> pq;
    pq.push(5);
    pq.push(3);
    pq.push(8);
    pq.push(1);

    cout << pq.top() << endl;
    */

    return 0;
}

二 图论算法

  1. dfs
#include 
#include 
#include 

using namespace std;

#define N 10005
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n;
vector G[N];
int color[N], d[N], f[N], tt;

void dfs_visit(int u)
{
    color[u] = GRAY;
    d[u] = ++tt;
    int v;
    for (int i = 0; i < G[u].size(); i++) {
        if (color[G[u][i]] == WHITE) { dfs_visit(G[u][i]); }
    }
    color[u] = BLACK;
    f[u] = ++tt;
}

void dfs()
{
    // init
    tt = 0;
    for (int i = 1; i <= n; i++) {
        color[i] = WHITE;
    }

    for (int i = 1; i <= n; i++) {
        if (color[i] == WHITE) { dfs_visit(i); }
    }

    for (int i = 1; i <= n; i++) {
        printf("%d %d %d\n", i, d[i], f[i]);
    }
}

int main()
{
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        int u, k;
        scanf(" %d %d", &u, &k);
        for (int j = 1; j <= k; j++) {
            int v; scanf(" %d", &v);
            G[u].push_back(v);
        }
    }

    dfs();

    return 0;
}
  1. bfs
#include 
#include 
#include 
#include 

using namespace std;

#define N 1005
#define WHITE 0
#define GRAY 1
#define BLACK 2
vector G[N];

int color[N], d[N];
int n;

void bfs(int s)
{
    // init
    for (int i = 1; i <= n; i++) {
        color[i] = WHITE;
        d[i] = -1;
    }

    queue q;
    q.push(s);
    d[s] = 0;

    while (!q.empty()) {
        int u = q.front(); q.pop();
        for (int i = 0; i < G[u].size(); i++) {
            int v = G[u][i];
            if (color[v] == WHITE) {
                // visit!
                color[v] = GRAY;
                d[v] = d[u] + 1;
                q.push(v);
            }
        }
        color[u] = BLACK;
    }

    for (int i = 1; i <= n; i++) {
        cout << i << " " << d[i] << endl;
    }
}

int main()
{
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        int u, k;
        scanf(" %d %d", &u, &k);
        for (int j = 1; j <= k; j++) {
            int v;
            scanf(" %d", &v);
            G[u].push_back(v);
            G[v].push_back(u);
        }
    }

    bfs(1);

    return 0;
}
  1. prim
#include 
#include 

using namespace std;

#define N 1005
#define INF (1<<30)
#define WHITE 0
#define GRAY 1
#define BLACK 2

int graph[N][N];
int n;

int prim(int s)
{
    // init
    int color[N], d[N], f[N];
    for (int i = 1; i <= n; i++) {
        color[i] = WHITE;
        d[i] = INF;
        f[i] = -1;
    }
    d[s] = 0;
    color[s] = GRAY;

    while (1) {
        int u = -1;
        int minu = INF;
        for (int v = 1; v <= n; v++) {
            if (color[v] != BLACK && d[v] < minu) {
                u = v;
                minu = d[v];
            }
        }
        if (u == -1) { break; }
        color[u] = BLACK;

        for (int v = 1; v <= n; v++) {
            if (graph[u][v] != -1 && color[v] != BLACK && graph[u][v] < d[v]) {
                d[v] = graph[u][v];
                f[v] = u;
                color[v] = GRAY;
            }
        }
    }

    int sum = 0;
    for (int i = 1; i <= n; i++) {
        if (f[i] != -1) {
            sum += graph[f[i]][i];
        }
    }
    printf("%d\n", sum);
}

int main()
{
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            scanf(" %d", &graph[i][j]);
        }
    }

    prim(1);

    return 0;
}
  1. dijkstra
#include 
#include 

using namespace std;

#define N 1005
#define INF (1<<30)
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n;
int graph[N][N];
int color[N], d[N], f[N];

void dijkstr(int s)
{
    // init
    for (int i = 0; i < n; i++) {
        color[i] = WHITE;
        d[i] = INF;
        f[i] = -1;
    }

    d[s] = 0;
    color[s] = GRAY;
    while (1) {
        int u = -1;
        int minu = INF;
        for (int i = 0; i < n; i++) {
            if (color[i] != BLACK && d[i] < minu) {
                u = i;
                minu = d[i];
            }
        }

        if (-1 == u) { break; }
        color[u] = BLACK;
        for (int v = 0; v < n; v++) {
            if (color[v] != BLACK && graph[u][v] != INF) {
                if (d[u] + graph[u][v] < d[v]) {
                    d[v] = d[u] + graph[u][v];
                    f[v] = u;
                    color[v] = GRAY;
                }
            }
        }
    }

    for (int i = 0; i < n; i++) {
        printf("%d %d\n", i, d[i]);
    }
}

int main()
{
    scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        for (int j = 0; j <= n; j++) {
            graph[i][j] = INF;
        }
    }

    for (int i = 0; i < n; i++) {
        int u, k;
        scanf(" %d %d", &u, &k);

        for (int j = 1; j <= k; j++) {
            int v, w;
            scanf(" %d %d", &v, &w);
            graph[u][v] = w;
            graph[v][u] = w;
        }
    }

    dijkstr(0);

    return 0;
}
  1. disset
#include 
#include 

using namespace std;

#define N 1005

int f[N];
int rankk[N];
int n, m;

void make_set(int n)
{
    for (int i = 0; i < n; i++) {
        f[i] = i;
        rankk[i] = 1;
    }
}

int find_f(int i)
{
    if (i != f[i]) {
        f[i] = find_f(f[i]);
    }

    return f[i];
}

void union_set(int x, int y)
{
    x = find_f(x);
    y = find_f(y);
    if (rankk[x] < rankk[y]) {
        f[x] = y;
    } else {
        f[y] = x;
        if (rankk[x] == rankk[y]) {
            rankk[x]++;
        }
    }
}

bool same(int x, int y)
{
    return find_f(x) == find_f(y);
}

int main()
{
    scanf("%d %d", &n, &m);

    // init
    make_set(n);

    for (int i = 1; i <= m; i++) {
        int type, x, y;
        scanf(" %d %d %d", &type, &x, &y);
        if (0 == type) {
            union_set(x, y);
        } else {
            if (same(x, y)) {
                printf("%d\n", 1);
            } else {
                printf("%d\n", 0);
            }
        }
    }

    return 0;
}
  1. floyd
#include 
#include 

using namespace std;

#define N 1005
#define INF (1<<30)
int graph[N][N];
int n, e;

void floyd()
{
    for (int k = 1; k <= n; k++) {
        for (int i = 1; i <= n; i++) {
            if (graph[i][k] == INF) { continue; }
            for (int j = 1; j <= n; j++) {
                if (graph[k][j] == INF) { continue; }
                if (graph[i][k] + graph[k][j] < graph[i][j]) {
                    graph[i][j] = graph[i][k] + graph[k][j];
                }
            }
        }
    }
}

int main()
{
    scanf("%d %d", &n, &e);
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            graph[i][j] = (i == j ? 0 : INF);
        }
    }

    for (int i = 1; i <= e; i++) {
        int u, v, w;
        scanf(" %d %d %d", &u, &v, &w);
        graph[u][v] = w;
    }

    floyd();

    bool flag = false;
    for (int i = 1; i <= n; i++) {
        if (graph[i][i] < 0) { flag = true; break; }
    }

    if (flag) { cout << "NEG!" << endl; }
    else {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                if (j-1) { cout << " "; }
                if (graph[i][j] == INF) {
                    cout << "INF";
                } else {
                    cout << graph[i][j];
                }
            }
            cout << endl;
        }
    }

    return 0;
}
  1. topo sort

#include 
#include 
#include 
#include 

using namespace std;

#define N 1005

int n, e;
vector G[N];
int ind[N];
bool visited[N];
vector out;

void topo()
{
    out.clear();
    memset(visited, 0, sizeof(visited));

    while (out.size() != n) {
        int u = -1;
        for (int i = 0; i < n; i++) {
            if (!visited[i] && ind[i] == 0) {
                out.push_back(i);
                u = i;
                visited[i] = true;

                for (int j = 0; j < G[i].size(); j++) {
                    int v = G[i][j];
                    ind[v]--;
                }
                break;
            }
        }

        if (-1 == u) { break; }
    }

    for (int i = 0; i < out.size(); i++) {
        if (i) { cout << " "; }
        cout << out[i];
    }
    cout << endl;
}


int main()
{
    scanf("%d %d", &n, &e);
    memset(ind, 0, sizeof(ind));

    for (int i = 0; i < e; i++) {
        int u, v;
        scanf(" %d %d", &u, &v);
        G[u].push_back(v);
        ind[v]++;
    }

    topo();

    return 0;
}

三 STL API

1 string

1.1 基本

  1. constructor
explicit string ( );
string ( const string& str );
string ( const string& str, size_t pos, size_t n = npos );
string ( const char * s, size_t n );
string ( const char * s );
string ( size_t n, char c );
template string (InputIterator begin, InputIterator end);

// string constructor
#include 
#include 
using namespace std;

int main ()
{
  // constructors used in the same order as described above:
  string s1;
  string s5 ("Initial string");
  string s2 (s5);
  string s3 (s5, 8, 3);
  string s4 (s5, 8);
  string s6 (10, 'x');
  string s7a (10, 42);
  string s7b (s5.c_str(), s5.c_str()+4);

  cout << "s1: " << s1 << "\ns2: " << s2 << "\ns3: " << s3;
  cout << "\ns4: " << s4 << "\ns5: " << s5 << "\ns6: " << s6;
  cout << "\ns7a: " << s7a << "\ns7b: " << s7b << endl;
  return 0;
}

output:
s1:
s2: Initial string
s3: str
s4: Initial
s5: Initial string
s6: xxxxxxxxxx
s7a: **********s
7b: Init

1.2 Iterator

  1. rbegin
reverse_iterator rbegin();
const_reverse_iterator rbegin() const;

// string::rbegin and string::rend
#include 
#include 
using namespace std;

int main ()
{
  string str ("now step live...");
  string::reverse_iterator rit;
  for ( rit=str.rbegin() ; rit < str.rend(); rit++ )
    cout << *rit;
  return 0;
}

1.3 Capacity

  1. resize
void resize ( size_t n, char c );
void resize ( size_t n );

Resizes the string content to n characters.
If n is smaller than the current length of the string, the content is reduced to its first n characters, the rest being dropped.
If n is greater than the current length of the string, the content is expanded by appending as many instances of the c character as needed to reach a size of n characters.　
The second version, actually calls: resize(n,char()), so when a string is resized to a greater size without passing a second argument, the new character positions are filled with the default value of a char, which is the null character.

// resizing string
#include 
#include 
using namespace std;

int main ()
{
  size_t sz;
  string str ("I like to code in C");
  cout << str << endl;

  sz=str.size();

  str.resize (sz+2,'+');
  cout << str << endl;

  str.resize (14);
  cout << str << endl;
  return 0;
}

1.4 Modifiers

  1. assign
string& assign ( const string& str );
string& assign ( const string&, size_t pos, size_t n );
string& assign ( const char* s, size_t n );
string& assign ( const char* s );
string& assign ( size_t n, char c );
template 
   string& assign ( InputIterator first, InputIterator last );

// string::assign
#include 
#include 
using namespace std;

int main ()
{
  string str;
  string base="The quick brown fox jumps over a lazy dog.";

  // used in the same order as described above:

  str.assign(base);
  cout << str << endl;

  str.assign(base,10,9);
  cout << str << endl;         // "brown fox"

  str.assign("pangrams are cool",7);
  cout << str << endl;         // "pangram"

  str.assign("c-string");
  cout << str << endl;         // "c-string"

  str.assign(10,'*');
  cout << str << endl;         // "**********"

  str.assign(10,0x2D);
  cout << str << endl;         // "----------"

  str.assign(base.begin()+16,base.end()-12);
  cout << str << endl;         // "fox jumps over"

  return 0;
}
  1. insert
string& insert ( size_t pos1, const string& str );
 string& insert ( size_t pos1, const string& str, size_t pos2, size_t n );
 string& insert ( size_t pos1, const char* s, size_t n);
 string& insert ( size_t pos1, const char* s );
 string& insert ( size_t pos1, size_t n, char c );
iterator insert ( iterator p, char c );
    void insert ( iterator p, size_t n, char c );
template
    void insert ( iterator p, InputIterator first, InputIterator last );

// inserting into a string
#include 
#include 
using namespace std;

int main ()
{
  string str="to be question";
  string str2="the ";
  string str3="or not to be";
  string::iterator it;

  // used in the same order as described above:
  str.insert(6,str2);                 // to be (the )question
  str.insert(6,str3,3,4);             // to be (not )the question
  str.insert(10,"that is cool",8);    // to be not (that is )the question
  str.insert(10,"to be ");            // to be not (to be )that is the question
  str.insert(15,1,':');               // to be not to be(:) that is the question
  it = str.insert(str.begin()+5,','); // to be(,) not to be: that is the question
  str.insert (str.end(),3,'.');       // to be, not to be: that is the question(...)
  str.insert (it+2,str3.begin(),str3.begin()+3); // (or )

  cout << str << endl;
  return 0;
}
  1. erase
string& erase ( size_t pos = 0, size_t n = npos );
iterator erase ( iterator position );
iterator erase ( iterator first, iterator last );

// string::erase
#include 
#include 
using namespace std;

int main ()
{
  string str ("This is an example phrase.");
  string::iterator it;

  // erase used in the same order as described above:
  str.erase (10,8);
  cout << str << endl;        // "This is an phrase."

  it=str.begin()+9;
  str.erase (it);
  cout << str << endl;        // "This is a phrase."

  str.erase (str.begin()+5, str.end()-7);
  cout << str << endl;        // "This phrase."
  return 0;
}
  1. replace
string& replace ( size_t pos1, size_t n1,   const string& str );
string& replace ( iterator i1, iterator i2, const string& str );

string& replace ( size_t pos1, size_t n1, const string& str, size_t pos2, size_t n2 );

string& replace ( size_t pos1, size_t n1,   const char* s, size_t n2 );
string& replace ( iterator i1, iterator i2, const char* s, size_t n2 );

string& replace ( size_t pos1, size_t n1,   const char* s );
string& replace ( iterator i1, iterator i2, const char* s );

string& replace ( size_t pos1, size_t n1,   size_t n2, char c );
string& replace ( iterator i1, iterator i2, size_t n2, char c );

template
   string& replace ( iterator i1, iterator i2, InputIterator j1, InputIterator j2 );

// replacing in a string
#include 
#include 
using namespace std;

int main ()
{
  string base="this is a test string.";
  string str2="n example";
  string str3="sample phrase";
  string str4="useful.";

  // function versions used in the same order as described above:

  // Using positions:                 0123456789*123456789*12345
  string str=base;                // "this is a test string."
  str.replace(9,5,str2);          // "this is an example string."
  str.replace(19,6,str3,7,6);     // "this is an example phrase."
  str.replace(8,10,"just all",6); // "this is just a phrase."
  str.replace(8,6,"a short");     // "this is a short phrase."
  str.replace(22,1,3,'!');        // "this is a short phrase!!!"

  // Using iterators:                      0123456789*123456789*
  string::iterator it = str.begin();   //  ^
  str.replace(it,str.end()-3,str3);    // "sample phrase!!!"
  str.replace(it,it+6,"replace it",7); // "replace phrase!!!"
  it+=8;                               //          ^
  str.replace(it,it+6,"is cool");      // "replace is cool!!!"
  str.replace(it+4,str.end()-4,4,'o'); // "replace is cooool!!!"
  it+=3;                               //             ^
  str.replace(it,str.end(),str4.begin(),str4.end());
                                       // "replace is useful."
  cout << str << endl;
  return 0;
}
  1. copy
size_t copy ( char* s, size_t n, size_t pos = 0) const;

// string::copy
#include 
#include 
using namespace std;

int main ()
{
  int length;
  char buffer[20];
  string str ("Test string...");
  length=str.copy(buffer,6,5);
  buffer[length]='\0';
  cout << "buffer contains: " << buffer << "\n";
  return 0;
}

1.5 String operations

  1. find
size_t find ( const string& str, size_t pos = 0 ) const;
size_t find ( const char* s, size_t pos, size_t n ) const;
size_t find ( const char* s, size_t pos = 0 ) const;
size_t find ( char c, size_t pos = 0 ) const;

// string::find
#include 
#include 
using namespace std;

int main ()
{
  string str ("There are two needles in this haystack with needles.");
  string str2 ("needle");
  size_t found;

  // different member versions of find in the same order as above:
  found=str.find(str2);
  if (found!=string::npos)
    cout << "first 'needle' found at: " << int(found) << endl;

  found=str.find("needles are small",found+1,6);
  if (found!=string::npos)
    cout << "second 'needle' found at: " << int(found) << endl;

  found=str.find("haystack");
  if (found!=string::npos)
    cout << "'haystack' also found at: " << int(found) << endl;

  found=str.find('.');
  if (found!=string::npos)
    cout << "Period found at: " << int(found) << endl;

  // let's replace the first needle:
  str.replace(str.find(str2),str2.length(),"preposition");
  cout << str << endl;

  return 0;
}
  1. rfind
size_t find ( const string& str, size_t pos = npos ) const;
size_t find ( const char* s, size_t pos, size_t n ) const;
size_t find ( const char* s, size_t pos = npos ) const;
size_t find ( char c, size_t pos = npos ) const;

// string::rfind
#include 
#include 
using namespace std;

int main ()
{
  string str ("The sixth sick sheik's sixth sheep's sick.");
  string key ("sixth");
  size_t found;

  found=str.rfind(key);
  if (found!=string::npos)
    str.replace (found,key.length(),"seventh");

  cout << str << endl;

  return 0;
}
  1. find_first_of
size_t find_first_of ( const string& str, size_t pos = 0 ) const;
size_t find_first_of ( const char* s, size_t pos, size_t n ) const;
size_t find_first_of ( const char* s, size_t pos = 0 ) const;
size_t find_first_of ( char c, size_t pos = 0 ) const;

// string::find_first_of
#include 
#include 
using namespace std;

int main ()
{
  string str ("Replace the vowels in this sentence by asterisks.");
  size_t found;

  found=str.find_first_of("aeiou");
  while (found!=string::npos)
  {
    str[found]='*';
    found=str.find_first_of("aeiou",found+1);
  }

  cout << str << endl;

  return 0;
}
  1. find_last_of
size_t find_last_of ( const string& str, size_t pos = npos ) const;
size_t find_last_of ( const char* s, size_t pos, size_t n ) const;
size_t find_last_of ( const char* s, size_t pos = npos ) const;
size_t find_last_of ( char c, size_t pos = npos ) const;

// string::find_last_of
#include 
#include 
using namespace std;

void SplitFilename (const string& str)
{
  size_t found;
  cout << "Splitting: " << str << endl;
  found=str.find_last_of("/\\");
  cout << " folder: " << str.substr(0,found) << endl;
  cout << " file: " << str.substr(found+1) << endl;
}

int main ()
{
  string str1 ("/usr/bin/man");
  string str2 ("c:\\windows\\winhelp.exe");

  SplitFilename (str1);
  SplitFilename (str2);

  return 0;
}
  1. find_first_not_of
size_t find_first_not_of ( const string& str, size_t pos = 0 ) const;
size_t find_first_not_of ( const char* s, size_t pos, size_t n ) const;
size_t find_first_not_of ( const char* s, size_t pos = 0 ) const;
size_t find_first_not_of ( char c, size_t pos = 0 ) const;

// string::find_first_not_of
#include 
#include 
using namespace std;

int main ()
{
  string str ("look for non-alphabetic characters...");
  size_t found;

  found=str.find_first_not_of("abcdefghijklmnopqrstuvwxyz ");
  if (found!=string::npos)
  {
    cout << "First non-alphabetic character is " << str[found];
    cout << " at position " << int(found) << endl;
  }

  return 0;
}
  1. find_last_not_of
size_t find_last_not_of ( const string& str, size_t pos = npos ) const;
size_t find_last_not_of ( const char* s, size_t pos, size_t n ) const;
size_t find_last_not_of ( const char* s, size_t pos = npos ) const;
size_t find_last_not_of ( char c, size_t pos = npos ) const;

// string::find_last_not_of
#include 
#include 
using namespace std;

int main ()
{
  string str ("erase trailing white-spaces   \n");
  string whitespaces (" \t\f\v\n\r");
  size_t found;
  
  found=str.find_last_not_of(whitespaces);
  if (found!=string::npos)
    str.erase(found+1);
  else
    str.clear();            // str is all whitespace

  cout << '"' << str << '"' << endl;

  return 0;
}
  1. substr
string substr ( size_t pos = 0, size_t n = npos ) const;

// string::substr
#include 
#include 
using namespace std;

int main ()
{
  string str="We think in generalities, but we live in details.";
                             // quoting Alfred N. Whitehead
  string str2, str3;
  size_t pos;

  str2 = str.substr (12,12); // "generalities"

  pos = str.find("live");      // position of "live" in str
  str3 = str.substr (pos);   // get from "live" to the end

  cout << str2 << ' ' << str3 << endl;

  return 0;
}
  1. compare
int compare ( const string& str ) const;
int compare ( const char* s ) const;
int compare ( size_t pos1, size_t n1, const string& str ) const;
int compare ( size_t pos1, size_t n1, const char* s) const;
int compare ( size_t pos1, size_t n1, const string& str, size_t pos2, size_t n2 ) const;
int compare ( size_t pos1, size_t n1, const char* s, size_t n2) const;

0 if the compared characters sequences are equal, otherwise a number different from 0 is returned, with its sign indicating whether the object is considered greater than the comparing string passed as parameter (positive sign), or smaller (negative sign).
If either pos1 or pos2 is specified with a position greater than the size of the corresponding string object, an exception of type out_of_range is thrown.

// comparing apples with apples
#include 
#include 
using namespace std;

int main ()
{
  string str1 ("green apple");
  string str2 ("red apple");

  if (str1.compare(str2) != 0)
    cout << str1 << " is not " << str2 << "\n";

  if (str1.compare(6,5,"apple") == 0)
    cout << "still, " << str1 << " is an apple\n";

  if (str2.compare(str2.size()-5,5,"apple") == 0)
    cout << "and " << str2 << " is also an apple\n";

  if (str1.compare(6,5,str2,4,5) == 0)
    cout << "therefore, both are apples\n";

  return 0;
}

2 stack

size empty top push pop

  • constructor
explicit stack ( const Container& ctnr = Container() );

// constructing stacks
#include 
#include 
#include 
#include 
using namespace std;

int main ()
{
  deque mydeque (3,100);     // deque with 3 elements
  vector myvector (2,200);   // vector with 2 elements

  stack first;               // empty stack
  stack second (mydeque);    // stack initialized to copy of deque

  stack > third;  // empty stack using vector
  stack > fourth (myvector);

  cout << "size of first: " << (int) first.size() << endl;
  cout << "size of second: " << (int) second.size() << endl;
  cout << "size of third: " << (int) third.size() << endl;
  cout << "size of fourth: " << (int) fourth.size() << endl;

  return 0;
}

3 queue

size empty front back push pop

  • constructor
explicit stack ( const Container& ctnr = Container() );

// constructing stacks
#include 
#include 
#include 
#include 
using namespace std;

int main ()
{
  deque mydeque (3,100);     // deque with 3 elements
  vector myvector (2,200);   // vector with 2 elements

  stack first;               // empty stack
  stack second (mydeque);    // stack initialized to copy of deque

  stack > third;  // empty stack using vector
  stack > fourth (myvector);

  cout << "size of first: " << (int) first.size() << endl;
  cout << "size of second: " << (int) second.size() << endl;
  cout << "size of third: " << (int) third.size() << endl;
  cout << "size of fourth: " << (int) fourth.size() << endl;

  return 0;
}

4 priority_queue

size empty top push pop

  • constructor
explicit priority_queue ( const Compare& x = Compare(),
                          const Container& y = Container() );
template 
         priority_queue ( InputIterator first, InputIterator last,
                          const Compare& x = Compare(),
                          const Container& y = Container() );

// constructing priority queues
#include 
#include 
using namespace std;

class mycomparison
{
  bool reverse;
public:
  mycomparison(const bool& revparam=false)
    {reverse=revparam;}
  bool operator() (const int& lhs, const int&rhs) const
  {
    if (reverse) return (lhs>rhs);
    else return (lhs first;
  priority_queue second (myints,myints+3);
  priority_queue< int, vector, greater > third (myints,myints+3);

  // using mycomparison:
  priority_queue< int, vector, mycomparison > fourth;

  typedef priority_queue,mycomparison> mypq_type;
  mypq_type fifth (mycomparison());
  mypq_type sixth (mycomparison(true));

  return 0;
}

5 set

5.1 member functions

  1. constructor
explicit set ( const Compare& comp = Compare(),
               const Allocator& = Allocator() );
template 
  set ( InputIterator first, InputIterator last,
        const Compare& comp = Compare(), const Allocator& = Allocator() );
set ( const set& x );

// constructing sets
#include 
#include 
using namespace std;

bool fncomp (int lhs, int rhs) {return lhs first;                           // empty set of ints

  int myints[]= {10,20,30,40,50};
  set second (myints,myints+5);        // pointers used as iterators

  set third (second);                  // a copy of second

  set fourth (second.begin(), second.end());  // iterator ctor.

  set fifth;                 // class as Compare

  bool(*fn_pt)(int,int) = fncomp;
  set sixth (fn_pt);  // function pointer as Compare

  return 0;
}

5.2 Iterator

  1. begin / end
// set::begin/end
#include 
#include 
using namespace std;

int main ()
{
  int myints[] = {75,23,65,42,13};
  set myset (myints,myints+5);

  set::iterator it;

  cout << "myset contains:";
  for ( it=myset.begin() ; it != myset.end(); it++ )
    cout << " " << *it;

  cout << endl;

  return 0;
}
  1. rbegin
// set::rbegin/rend
#include 
#include 
using namespace std;

int main ()
{
  int myints[] = {78,21,64,49,17};
  set myset (myints,myints+5);

  set::reverse_iterator rit;

  cout << "myset contains:";
  for ( rit=myset.rbegin() ; rit != myset.rend(); rit++ )
    cout << " " << *rit;

  cout << endl;

  return 0;
}

5.3 Modifier

  1. insert
pair insert ( const value_type& x );
           iterator insert ( iterator position, const value_type& x );
template 
      void insert ( InputIterator first, InputIterator last );

// set::insert
#include 
#include 
using namespace std;

int main ()
{
  set myset;
  set::iterator it;
  pair::iterator,bool> ret;

  // set some initial values:
  for (int i=1; i<=5; i++) myset.insert(i*10);    // set: 10 20 30 40 50

  ret = myset.insert(20);               // no new element inserted

  if (ret.second==false) it=ret.first;  // "it" now points to element 20

  myset.insert (it,25);                 // max efficiency inserting
  myset.insert (it,24);                 // max efficiency inserting
  myset.insert (it,26);                 // no max efficiency inserting

  int myints[]= {5,10,15};              // 10 already in set, not inserted
  myset.insert (myints,myints+3);

  cout << "myset contains:";
  for (it=myset.begin(); it!=myset.end(); it++)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. erase
void erase ( iterator position );
size_type erase ( const key_type& x );
     void erase ( iterator first, iterator last );

// erasing from set
#include 
#include 
using namespace std;

int main ()
{
  set myset;
  set::iterator it;

  // insert some values:
  for (int i=1; i<10; i++) myset.insert(i*10);  // 10 20 30 40 50 60 70 80 90

  it=myset.begin();
  it++;                                         // "it" points now to 20

  myset.erase (it);

  myset.erase (40);

  it=myset.find (60);
  myset.erase ( it, myset.end() );

  cout << "myset contains:";
  for (it=myset.begin(); it!=myset.end(); ++it)
    cout << " " << *it;
  cout << endl;

  return 0;
}

5.4 Observers

  1. key_comp
key_compare key_comp ( ) const;

// set::key_comp
#include 
#include 
using namespace std;

int main ()
{
  set myset;
  set::key_compare mycomp;
  set::iterator it;
  int i,highest;

  mycomp = myset.key_comp();

  for (i=0; i<=5; i++) myset.insert(i);

  cout << "myset contains:";

  highest=*myset.rbegin();
  it=myset.begin();
  do {
    cout << " " << *it;
  } while ( mycomp(*it++,highest) );

  cout << endl;

  return 0;
}
  1. value_comp
value_compare value_comp ( ) const;

// set::value_comp
#include 
#include 
using namespace std;

int main ()
{
  set myset;
  set::value_compare mycomp;
  set::iterator it;
  int i,highest;

  mycomp = myset.value_comp();

  for (i=0; i<=5; i++) myset.insert(i);

  cout << "myset contains:";

  highest=*myset.rbegin();
  it=myset.begin();
  do {
    cout << " " << *it;
  } while ( mycomp(*it++,highest) );

  cout << endl;

  return 0;
}

5.5 Operations

  1. find
iterator find ( const key_type& x ) const;

// set::find
#include 
#include 
using namespace std;

int main ()
{
  set myset;
  set::iterator it;

  // set some initial values:
  for (int i=1; i<=5; i++) myset.insert(i*10);    // set: 10 20 30 40 50

  it=myset.find(20);
  myset.erase (it);
  myset.erase (myset.find(40));

  cout << "myset contains:";
  for (it=myset.begin(); it!=myset.end(); it++)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. count
size_type count ( cont key_type& x ) const;

// set::count
#include 
#include 
using namespace std;

int main ()
{
  set myset;
  int i;

  // set some initial values:
  for (i=1; i<5; i++) myset.insert(i*3);    // set: 3 6 9 12

  for (i=0;i<10; i++)
  {
    cout << i;
    if (myset.count(i)>0)
      cout << " is an element of myset.\n";
    else 
      cout << " is not an element of myset.\n";
  }

  return 0;
}

output:
0 is not an element of myset.
1 is not an element of myset.
2 is not an element of myset.
3 is an element of myset.
4 is not an element of myset.
5 is not an element of myset.
6 is an element of myset.
7 is not an element of myset.
8 is not an element of myset.
9 is an element of myset.

  1. lower_bound
iterator lower_bound ( const key_type& x ) const;

// set::lower_bound/upper_bound
#include 
#include 
using namespace std;

int main ()
{
  set myset;
  set::iterator it,itlow,itup;

  for (int i=1; i<10; i++) myset.insert(i*10); // 10 20 30 40 50 60 70 80 90

  itlow=myset.lower_bound (30);                //       ^
  itup=myset.upper_bound (60);                 //                   ^

  myset.erase(itlow,itup);                     // 10 20 70 80 90

  cout << "myset contains:";
  for (it=myset.begin(); it!=myset.end(); it++)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. upper_bound
iterator upper_bound ( const key_type& x ) const;

// set::lower_bound/upper_bound
#include 
#include 
using namespace std;

int main ()
{
  set myset;
  set::iterator it,itlow,itup;

  for (int i=1; i<10; i++) myset.insert(i*10); // 10 20 30 40 50 60 70 80 90

  itlow=myset.lower_bound (30);                //       ^
  itup=myset.upper_bound (60);                 //                   ^

  myset.erase(itlow,itup);                     // 10 20 70 80 90

  cout << "myset contains:";
  for (it=myset.begin(); it!=myset.end(); it++)
    cout << " " << *it;
  cout << endl;

  return 0;
}

6 map

6.1 Member functions

  1. constructor
explicit map ( const Compare& comp = Compare(),
               const Allocator& = Allocator() );
template 
  map ( InputIterator first, InputIterator last,
        const Compare& comp = Compare(), const Allocator& = Allocator() );
map ( const map& x );

// constructing maps
#include 
#include 
using namespace std;

bool fncomp (char lhs, char rhs) {return lhs first;

  first['a']=10;
  first['b']=30;
  first['c']=50;
  first['d']=70;

  map second (first.begin(),first.end());

  map third (second);

  map fourth;                 // class as Compare

  bool(*fn_pt)(char,char) = fncomp;
  map fifth (fn_pt); // function pointer as Compare

  return 0;
}

6.2 Iterators

  1. begin
iterator begin ();
const_iterator begin () const;

// map::begin/end
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::iterator it;

  mymap['b'] = 100;
  mymap['a'] = 200;
  mymap['c'] = 300;

  // show content:
  for ( it=mymap.begin() ; it != mymap.end(); it++ )
    cout << (*it).first << " => " << (*it).second << endl;

  return 0;
}
  1. rbegin
reverse_iterator rbegin();
const_reverse_iterator rbegin() const;

// map::rbegin/rend
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::reverse_iterator rit;

  mymap['x'] = 100;
  mymap['y'] = 200;
  mymap['z'] = 300;

  // show content:
  for ( rit=mymap.rbegin() ; rit != mymap.rend(); rit++ )
    cout << rit->first << " => " << rit->second << endl;

  return 0;
}

6.3 Modifiers

  1. insert
pair insert ( const value_type& x );
           iterator insert ( iterator position, const value_type& x );
template 
      void insert ( InputIterator first, InputIterator last );

// map::insert
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::iterator it;
  pair::iterator,bool> ret;

  // first insert function version (single parameter):
  mymap.insert ( pair('a',100) );
  mymap.insert ( pair('z',200) );
  ret=mymap.insert (pair('z',500) ); 
  if (ret.second==false)
  {
    cout << "element 'z' already existed";
    cout << " with a value of " << ret.first->second << endl;
  }

  // second insert function version (with hint position):
  it=mymap.begin();
  mymap.insert (it, pair('b',300));  // max efficiency inserting
  mymap.insert (it, pair('c',400));  // no max efficiency inserting

  // third insert function version (range insertion):
  map anothermap;
  anothermap.insert(mymap.begin(),mymap.find('c'));

  // showing contents:
  cout << "mymap contains:\n";
  for ( it=mymap.begin() ; it != mymap.end(); it++ )
    cout << (*it).first << " => " << (*it).second << endl;

  cout << "anothermap contains:\n";
  for ( it=anothermap.begin() ; it != anothermap.end(); it++ )
    cout << (*it).first << " => " << (*it).second << endl;

  return 0;
}
  1. erase
void erase ( iterator position );
size_type erase ( const key_type& x );
     void erase ( iterator first, iterator last );

// erasing from map
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::iterator it;

  // insert some values:
  mymap['a']=10;
  mymap['b']=20;
  mymap['c']=30;
  mymap['d']=40;
  mymap['e']=50;
  mymap['f']=60;

  it=mymap.find('b');
  mymap.erase (it);                   // erasing by iterator

  mymap.erase ('c');                  // erasing by key

  it=mymap.find ('e');
  mymap.erase ( it, mymap.end() );    // erasing by range

  // show content:
  for ( it=mymap.begin() ; it != mymap.end(); it++ )
    cout << (*it).first << " => " << (*it).second << endl;

  return 0;
}

6.4 Observers

  1. key_comp
key_compare key_comp ( ) const;

// map::key_comp
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::key_compare mycomp;
  map::iterator it;
  char highest;

  mycomp = mymap.key_comp();

  mymap['a']=100;
  mymap['b']=200;
  mymap['c']=300;

  cout << "mymap contains:\n";

  highest=mymap.rbegin()->first;     // key value of last element

  it=mymap.begin();
  do {
    cout << (*it).first << " => " << (*it).second << endl;
  } while ( mycomp((*it++).first, highest) );

  cout << endl;

  return 0;
}
  1. value_comp
value_compare value_comp ( ) const;

// map::value_comp
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::iterator it;
  pair highest;

  mymap['x']=1001;
  mymap['y']=2002;
  mymap['z']=3003;

  cout << "mymap contains:\n";

  highest=*mymap.rbegin();          // last element

  it=mymap.begin();
  do {
    cout << (*it).first << " => " << (*it).second << endl;
  } while ( mymap.value_comp()(*it++, highest) );

  return 0;
}

6.5 Operations

  1. find
iterator find ( const key_type& x );
const_iterator find ( const key_type& x ) const;

// map::find
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::iterator it;

  mymap['a']=50;
  mymap['b']=100;
  mymap['c']=150;
  mymap['d']=200;

  it=mymap.find('b');
  mymap.erase (it);
  mymap.erase (mymap.find('d'));

  // print content:
  cout << "elements in mymap:" << endl;
  cout << "a => " << mymap.find('a')->second << endl;
  cout << "c => " << mymap.find('c')->second << endl;

  return 0;
}
  1. count
size_type count ( cont key_type& x ) const;

// map::count
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  char c;

  mymap ['a']=101;
  mymap ['c']=202;
  mymap ['f']=303;

  for (c='a'; c<'h'; c++)
  {
    cout << c;
    if (mymap.count(c)>0)
      cout << " is an element of mymap.\n";
    else 
      cout << " is not an element of mymap.\n";
  }

  return 0;
}
  1. lower_bound
iterator lower_bound ( const key_type& x );
const_iterator lower_bound ( const key_type& x ) const;

// map::lower_bound/upper_bound
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::iterator it,itlow,itup;

  mymap['a']=20;
  mymap['b']=40;
  mymap['c']=60;
  mymap['d']=80;
  mymap['e']=100;

  itlow=mymap.lower_bound ('b');  // itlow points to b
  itup=mymap.upper_bound ('d');   // itup points to e (not d!)

  mymap.erase(itlow,itup);        // erases [itlow,itup)

  // print content:
  for ( it=mymap.begin() ; it != mymap.end(); it++ )
    cout << (*it).first << " => " << (*it).second << endl;

  return 0;
}
  1. upper_bound
iterator upper_bound ( const key_type& x );
const_iterator upper_bound ( const key_type& x ) const;

// map::lower_bound/upper_bound
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  map::iterator it,itlow,itup;

  mymap['a']=20;
  mymap['b']=40;
  mymap['c']=60;
  mymap['d']=80;
  mymap['e']=100;

  itlow=mymap.lower_bound ('b');  // itlow points to b
  itup=mymap.upper_bound ('d');   // itup points to e (not d!)

  mymap.erase(itlow,itup);        // erases [itlow,itup)

  // print content:
  for ( it=mymap.begin() ; it != mymap.end(); it++ )
    cout << (*it).first << " => " << (*it).second << endl;

  return 0;
}
  1. equal_range
pair
   equal_range ( const key_type& x );
pair
   equal_range ( const key_type& x ) const;

// map::equal_elements
#include 
#include 
using namespace std;

int main ()
{
  map mymap;
  pair::iterator,map::iterator> ret;

  mymap['a']=10;
  mymap['b']=20;
  mymap['c']=30;

  ret = mymap.equal_range('b');

  cout << "lower bound points to: ";
  cout << ret.first->first << " => " << ret.first->second << endl;

  cout << "upper bound points to: ";
  cout << ret.second->first << " => " << ret.second->second << endl;

  return 0;
}

7 vector

7.1 Modifiers

  1. assign
template 
  void assign ( InputIterator first, InputIterator last );
void assign ( size_type n, const T& u );

// vector assign
#include 
#include 
using namespace std;

int main ()
{
  vector first;
  vector second;
  vector third;

  first.assign (7,100);             // a repetition 7 times of value 100

  vector::iterator it;
  it=first.begin()+1;

  second.assign (it,first.end()-1); // the 5 central values of first

  int myints[] = {1776,7,4};
  third.assign (myints,myints+3);   // assigning from array.

  cout << "Size of first: " << int (first.size()) << endl;
  cout << "Size of second: " << int (second.size()) << endl;
  cout << "Size of third: " << int (third.size()) << endl;
  return 0;
}
  1. insert
iterator insert ( iterator position, const T& x );
    void insert ( iterator position, size_type n, const T& x );
template 
    void insert ( iterator position, InputIterator first, InputIterator last );

#include 
#include 
using namespace std;

int main ()
{
  vector myvector (3,100);
  vector::iterator it;

  it = myvector.begin();
  it = myvector.insert ( it , 200 );

  myvector.insert (it,2,300);

  // "it" no longer valid, get a new one:
  it = myvector.begin();

  vector anothervector (2,400);
  myvector.insert (it+2,anothervector.begin(),anothervector.end());

  int myarray [] = { 501,502,503 };
  myvector.insert (myvector.begin(), myarray, myarray+3);

  cout << "myvector contains:";
  for (it=myvector.begin(); it
  1. erase
iterator erase ( iterator position );
iterator erase ( iterator first, iterator last );

// erasing from vector
#include 
#include 
using namespace std;

int main ()
{
  unsigned int i;
  vector myvector;

  // set some values (from 1 to 10)
  for (i=1; i<=10; i++) myvector.push_back(i);
  
  // erase the 6th element
  myvector.erase (myvector.begin()+5);

  // erase the first 3 elements:
  myvector.erase (myvector.begin(),myvector.begin()+3);

  cout << "myvector contains:";
  for (i=0; i

8 list

8.1 Modifiers

  1. insert
iterator insert ( iterator position, const T& x );
    void insert ( iterator position, size_type n, const T& x );
template 
    void insert ( iterator position, InputIterator first, InputIterator last );

#include 
#include 
#include 
using namespace std;

int main ()
{
  list mylist;
  list::iterator it;

  // set some initial values:
  for (int i=1; i<=5; i++) mylist.push_back(i); // 1 2 3 4 5

  it = mylist.begin();
  ++it;       // it points now to number 2           ^

  mylist.insert (it,10);                        // 1 10 2 3 4 5

  // "it" still points to number 2                      ^
  mylist.insert (it,2,20);                      // 1 10 20 20 2 3 4 5

  --it;       // it points now to the second 20            ^

  vector myvector (2,30);
  mylist.insert (it,myvector.begin(),myvector.end());
                                                // 1 10 20 30 30 20 2 3 4 5
                                                //               ^
  cout << "mylist contains:";
  for (it=mylist.begin(); it!=mylist.end(); it++)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. erase
iterator erase ( iterator position );
iterator erase ( iterator first, iterator last );

// erasing from list
#include 
#include 
using namespace std;

int main ()
{
  unsigned int i;
  list mylist;
  list::iterator it1,it2;

  // set some values:
  for (i=1; i<10; i++) mylist.push_back(i*10);

                              // 10 20 30 40 50 60 70 80 90
  it1 = it2 = mylist.begin(); // ^^
  advance (it2,6);            // ^                 ^
  ++it1;                      //    ^              ^

  it1 = mylist.erase (it1);   // 10 30 40 50 60 70 80 90
                              //    ^           ^

  it2 = mylist.erase (it2);   // 10 30 40 50 60 80 90
                              //    ^           ^

  ++it1;                      //       ^        ^
  --it2;                      //       ^     ^

  mylist.erase (it1,it2);     // 10 30 60 80 90
                              //        ^

  cout << "mylist contains:";
  for (it1=mylist.begin(); it1!=mylist.end(); ++it1)
    cout << " " << *it1;
  cout << endl;

  return 0;
}

8.2 Operations

  1. splice
void splice ( iterator position, list& x );
void splice ( iterator position, list& x, iterator i );
void splice ( iterator position, list& x, iterator first, iterator last );

// splicing lists
#include 
#include 
using namespace std;

int main ()
{
  list mylist1, mylist2;
  list::iterator it;

  // set some initial values:
  for (int i=1; i<=4; i++)
     mylist1.push_back(i);      // mylist1: 1 2 3 4

  for (int i=1; i<=3; i++)
     mylist2.push_back(i*10);   // mylist2: 10 20 30

  it = mylist1.begin();
  ++it;                         // points to 2

  mylist1.splice (it, mylist2); // mylist1: 1 10 20 30 2 3 4
                                // mylist2 (empty)
                                // "it" still points to 2 (the 5th element)

  mylist2.splice (mylist2.begin(),mylist1, it);
                                // mylist1: 1 10 20 30 3 4
                                // mylist2: 2
                                // "it" is now invalid.
  it = mylist1.begin();
  advance(it,3);                // "it" points now to 30

  mylist1.splice ( mylist1.begin(), mylist1, it, mylist1.end());
                                // mylist1: 30 3 4 1 10 20

  cout << "mylist1 contains:";
  for (it=mylist1.begin(); it!=mylist1.end(); it++)
    cout << " " << *it;

  cout << "\nmylist2 contains:";
  for (it=mylist2.begin(); it!=mylist2.end(); it++)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. remove
void remove ( const T& value );

#include 
#include 
using namespace std;

int main ()
{
  int myints[]= {17,89,7,14};
  list mylist (myints,myints+4);

  mylist.remove(89);

  cout << "mylist contains:";
  for (list::iterator it=mylist.begin(); it!=mylist.end(); ++it)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. remove_if
template 
  void remove_if ( Predicate pred );

// list::remove_if
#include 
#include 
using namespace std;

// a predicate implemented as a function:
bool single_digit (const int& value) { return (value<10); }

// a predicate implemented as a class:
class is_odd
{
public:
  bool operator() (const int& value) {return (value%2)==1; }
};

int main ()
{
  int myints[]= {15,36,7,17,20,39,4,1};
  list mylist (myints,myints+8);   // 15 36 7 17 20 39 4 1

  mylist.remove_if (single_digit);      // 15 36 17 20 39

  mylist.remove_if (is_odd());          // 36 20

  cout << "mylist contains:";
  for (list::iterator it=mylist.begin(); it!=mylist.end(); ++it)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. unique // 需要先排序
void unique ( );
template 
  void unique ( BinaryPredicate binary_pred );

// list::unique
#include 
#include 
#include 
using namespace std;

// a binary predicate implemented as a function:
bool same_integral_part (double first, double second)
{ return ( int(first)==int(second) ); }

// a binary predicate implemented as a class:
class is_near
{
public:
  bool operator() (double first, double second)
  { return (fabs(first-second)<5.0); }
};

int main ()
{
  double mydoubles[]={ 12.15,  2.72, 73.0,  12.77,  3.14,
                       12.77, 73.35, 72.25, 15.3,  72.25 };
  list mylist (mydoubles,mydoubles+10);
  
  mylist.sort();             //  2.72,  3.14, 12.15, 12.77, 12.77,
                             // 15.3,  72.25, 72.25, 73.0,  73.35

  mylist.unique();           //  2.72,  3.14, 12.15, 12.77
                             // 15.3,  72.25, 73.0,  73.35

  mylist.unique (same_integral_part);  //  2.72,  3.14, 12.15
                                       // 15.3,  72.25, 73.0

  mylist.unique (is_near());           //  2.72, 12.15, 72.25

  cout << "mylist contains:";
  for (list::iterator it=mylist.begin(); it!=mylist.end(); ++it)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. merge
void merge ( list& x );
template 
  void merge ( list& x, Compare comp );

// list::merge
#include 
#include 
using namespace std;

// this compares equal two doubles if
//  their interger equivalents are equal
bool mycomparison (double first, double second)
{ return ( int(first) first, second;

  first.push_back (3.1);
  first.push_back (2.2);
  first.push_back (2.9);

  second.push_back (3.7);
  second.push_back (7.1);
  second.push_back (1.4);

  first.sort();
  second.sort();

  first.merge(second);

  second.push_back (2.1);

  first.merge(second,mycomparison);

  cout << "first contains:";
  for (list::iterator it=first.begin(); it!=first.end(); ++it)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. sort
void sort ( );
template 
  void sort ( Compare comp );

// list::sort
#include 
#include 
#include 
#include 
using namespace std;

// comparison, not case sensitive.
bool compare_nocase (string first, string second)
{
  unsigned int i=0;
  while ( (i mylist;
  list::iterator it;
  mylist.push_back ("one");
  mylist.push_back ("two");
  mylist.push_back ("Three");

  mylist.sort();

  cout << "mylist contains:";
  for (it=mylist.begin(); it!=mylist.end(); ++it)
    cout << " " << *it;
  cout << endl;

  mylist.sort(compare_nocase);

  cout << "mylist contains:";
  for (it=mylist.begin(); it!=mylist.end(); ++it)
    cout << " " << *it;
  cout << endl;

  return 0;
}
  1. reverse
// reversing vector
#include 
#include 
using namespace std;

int main ()
{
  list mylist;
  list::iterator it;

  for (int i=1; i<10; i++) mylist.push_back(i);

  mylist.reverse();

  cout << "mylist contains:";
  for (it=mylist.begin(); it!=mylist.end(); ++it)
    cout << " " << *it;

  cout << endl;

  return 0;
}

9 cstdio

  1. sprintf & sscanf
/// sprintf 将数据存储到字符串中
char* str = "sadada ";

char s[100];
int d = 12;
float fff = 20.8;
sprintf(s, "%s %d %.2f", str, d, fff); // 把其他格式转成C-String类型

cout << s << endl; // sadada  12 20.80

int data = 100;
char s_data[100];
sprintf(s_data, "0x%X", data); // 16进制
cout << s_data << endl;

sprintf(s_data, "0%o", data); // 8进制
cout << s_data << endl;

/// sscanf 从字符串中提取数据
char* ss = "12 12.8";
int dd;
float ff;
sscanf(ss, "%d %f", &dd, &ff);
cout << dd << endl;
cout << ff << endl;

const char *szhi = "http://www.baidu.com:1234";
char protocol[32] = { 0 };
char host[128] = { 0 };
char port[8] = { 0 };
sscanf(szhi, "%[^:]://%[^:]:%[1-9]", protocol, host, port);

printf("protocol: %s\n", protocol);
printf("host: %s\n", host);
printf("port: %s\n", port);

10 cstring

10.1 Copying

  1. memcpy
void * memcpy ( void * destination, const void * source, size_t num );

#include 
#include 

int main ()
{
  char str1[]="Sample string";
  char str2[40];
  char str3[40];
  memcpy (str2,str1,strlen(str1)+1);
  memcpy (str3,"copy successful",16);
  printf ("str1: %s\nstr2: %s\nstr3: %s\n",str1,str2,str3);
  return 0;
}
  1. strcpy
char * strcpy ( char * destination, const char * source );

#include 
#include 

int main ()
{
  char str1[]="Sample string";
  char str2[40];
  char str3[40];
  strcpy (str2,str1);
  strcpy (str3,"copy successful");
  printf ("str1: %s\nstr2: %s\nstr3: %s\n",str1,str2,str3);
  return 0;
}
  1. strncpy
char * strncpy ( char * destination, const char * source, size_t num );

#include 
#include 

int main ()
{
  char str1[]= "To be or not to be";
  char str2[6];
  strncpy (str2,str1,5);
  str2[5]='\0';
  puts (str2);
  return 0;
}

10.2 Concatenation

  1. strcat
char * strcat ( char * destination, const char * source );

#include 
#include 

int main ()
{
  char str[80];
  strcpy (str,"these ");
  strcat (str,"strings ");
  strcat (str,"are ");
  strcat (str,"concatenated.");
  puts (str);
  return 0;
}
  1. strncat
char * strncat ( char * destination, char * source, size_t num );

/* strncat example */
#include 
#include 

int main ()
{
  char str1[20];
  char str2[20];
  strcpy (str1,"To be ");
  strcpy (str2,"or not to be");
  strncat (str1, str2, 6);
  puts (str1);
  return 0;
}

10.3 Comparison

  1. strcmp
int strcmp ( const char * str1, const char * str2 );

Returns an integral value indicating the relationship between the strings:
A zero value indicates that both strings are equal.
A value greater than zero indicates that the first character that does not match has a greater value in str1 than in str2; And a value less than zero indicates the opposite.

#include 
#include 

int main ()
{
  char szKey[] = "apple";
  char szInput[80];
  do {
     printf ("Guess my favourite fruit? ");
     gets (szInput);
  } while (strcmp (szKey,szInput) != 0);
  puts ("Correct answer!");
  return 0;
}

10.4 Searching

  1. strchr
const char * strchr ( const char * str, int character );
      char * strchr (       char * str, int character );

#include 
#include 

int main ()
{
  char str[] = "This is a sample string";
  char * pch;
  printf ("Looking for the 's' character in \"%s\"...\n",str);
  pch=strchr(str,'s');
  while (pch!=NULL)
  {
    printf ("found at %d\n",pch-str+1);
    pch=strchr(pch+1,'s');
  }
  return 0;
}
  1. strcspn /// 出现指定的
size_t strcspn ( const char * str1, const char * str2 );

#include 
#include 

int main ()
{
  char str[] = "fcba73";
  char keys[] = "1234567890";
  int i;
  i = strcspn (str,keys);
  printf ("The first number in str is at position %d.\n",i+1);
  return 0;
}
  1. strspn /// 未出现指定的
size_t strspn ( const char * str1, const char * str2 );

#include 
#include 

int main ()
{
  int i;
  char strtext[] = "129th";
  char cset[] = "1234567890";

  i = strspn (strtext,cset);
  printf ("The length of initial number is %d.\n",i);
  return 0;
}
  1. strstr
const char * strstr ( const char * str1, const char * str2 );
      char * strstr (       char * str1, const char * str2 );

#include 
#include 

int main ()
{
  char str[] ="This is a simple string";
  char * pch;
  pch = strstr (str,"simple");
  strncpy (pch,"sample",5);
  puts (str);
  return 0;
}
  1. strtok
// strings and c-strings
#include 
#include 
#include 
using namespace std;

int main ()
{
  char * cstr, *p;

  string str ("Please split this phrase into tokens");

  cstr = new char [str.size()+1];
  strcpy (cstr, str.c_str());

  // cstr now contains a c-string copy of str

  p=strtok (cstr," ");
  while (p!=NULL)
  {
    cout << p << endl;;
    p=strtok(NULL," ");
  }

  delete[] cstr;  
  return 0;
}

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