C++学习笔记(字符串string、vector_deque、queue,multiset、map、multimap、容器拷贝问题)(复制粘贴,方便后面翻阅)

1.string操作

#include <iostream>
#include <string>
#include <algorithm> //算法

using namespace std;

//STL standard template libary 标准模(mu)板库 C++一部分，编译器自带
//Android NDK支持
//java.lang java.util包中API，java的一部分

//string初始化

void main()
{
    //string由c字符串衍生过来的
    string s1 = "craig david";
    string s2("7 days");
    string s3 = s2;
    string s4(10,'a');

    cout << s4 << endl;

    system("pause");
}

//string遍历
void main()
{
    string s1 = "craig david";
    // ^
    //1 数组方式
    for (int i = 0; i < s1.length(); i++)
    {
        cout << s1[i] << endl;
    }
    //2 迭代器指针
    for (string::iterator it = s1.begin(); it != s1.end(); it++)
    {
        cout << *it << " ";
    }
    cout << endl;
    //3 at函数(charAt)
    // 可能会抛出异常
    try
    {
        for (int i = 0; i < s1.length() + 3; i++)
        {
            cout << s1.at(i) << " ";
        }
    }
    catch (...)
    {
        cout << "异常" << endl;
    }


    system("pause");
}


//string字符串->c字符串转换
void main()
{
    //string -> char*
    string s1 = "walking away";
    const char* c = s1.c_str();
    printf("%s\n",c);

    //
    string s2 = c;

    //string->char[]
    //从string中赋值字符到char[]
    char arr[50] = {0};
    s1.copy(arr,4,0);

    cout << arr << endl;

    system("pause");
}


//字符串拼接
void main()
{
    string s1 = "alan";
    string s2 = "jackson";

    //1.
    string s3 = s1 + s2;

    string s4 = " pray";

    //2.
    s3.append(s4);

    cout << s3 << endl;

    system("pause");
}

//字符串查找替换
void main()
{
    string s1 = "apple google apple iphone";
    //从0开始查找"google"的位置
    int idx = s1.find("google", 0);
    cout << idx << endl;

    //统计apple出现的次数
    int idx_app = s1.find("apple",0);
    //npos大于任何有效下标的值
    int num = 0;
    while (idx_app != string::npos)
    {
        num++;
        cout << "找到的索引:" << idx_app << endl;
        idx_app+=5;
        idx_app = s1.find("apple", idx_app);
    }

    cout << num << endl;
    system("pause");
}

void main()
{
    string s1 = "apple google apple iphone";
    //0-5（不包含5）替换为jobs
    s1.replace(0, 5, "jobs");
    cout << s1 << endl;

    //所有apple替换为jobs
    int idx = s1.find("apple", 0);
    while (idx != string::npos)
    {
        s1.replace(idx, 5, "jobs");
        idx += 5;
        idx = s1.find("apple", idx);
    }

    cout << s1 << endl;
    system("pause");
}

//删除（截取）和插入
void main()
{
    string s1 = "apple google apple iphone";
    //删除a，找到a所在的指针
    string::iterator it = find(s1.begin(),s1.end(),'g');
    //只能删除一个字符
    s1.erase(it);

    //开头末尾插入字符串
    s1.insert(0, "macos");
    s1.insert(s1.length(), " facebook");

    cout << s1 << endl;
    system("pause");
}

//java StringBuffer才可变
//String 不可变
//大小写转换
void main()
{
    string s1 = "JASON";
    //原始字符串的起始地址，原始字符串的结束地址, 目标字符串的起始地址, 函数名称
    transform(s1.begin(), s1.end()-1,s1.begin(), tolower);
    cout << s1 << endl;


    transform(s1.begin(), s1.end() - 1, s1.begin(), toupper);
    cout << s1 << endl;

    system("pause");
}

2.容器vector

//容器
//Vector
//初始化
#include <vector>
void printVector(vector<int> &v)
{
    //通过数组的方式遍历
    for (int i = 0; i < v.size(); i++)
    {
        cout << v[i] << endl;
    }
}
void main()
{
    //1.
    vector<int> v1;
    v1.push_back(20);
    v1.push_back(40);
    v1.push_back(15);
    v1.push_back(7);

    //2.
    vector<int> v2 = v1;

    //3.部分复制
    vector<int> v3(v1.begin(),v1.begin()+2);

    printVector(v3);


    system("pause");
}

//添加 删除
void main()
{
    //添加到结尾
    vector<int> v1;
    v1.push_back(20);
    v1.push_back(40);
    v1.push_back(15);
    v1.push_back(7);

    //访问头部
    v1.front() = 11;
    //访问尾部
    v1.back() = 90;

    //删除结尾的元素
    //v1.pop_back();
    while (v1.size() > 0)
    {
        cout << "末尾的元素：" << v1.back() << endl;
        v1.pop_back();
    }

    printVector(v1);

    system("pause");
}

//数组的方式
void main()
{
    vector<int> v1;
    v1.push_back(20);
    v1.push_back(40);
    v1.push_back(15);
    v1.push_back(7);

    v1[2] = v1[2] +10;

    //容器等价于动态数组 
    vector<int> v2(10);
    for (int i = 0; i < v2.size(); i++)
    {
        v2[i] = i + 1;
    }

    printVector(v2);

    system("pause");
}

//迭代器遍历
//迭代器的种类（正向，反向迭代器）
void main()
{
    vector<int> v1;
    v1.push_back(20);
    v1.push_back(40);
    v1.push_back(15);
    v1.push_back(7);
    //正向
    for (vector<int>::iterator it = v1.begin(); it < v1.end(); it++)
    {
        cout << *it << endl;
    }
    cout << "-----------------" << endl;
    //反向迭代
    for (vector<int>::reverse_iterator it = v1.rbegin(); it < v1.rend(); it++)
    {
        cout << *it << endl;
    }

    system("pause");
}

//删除
void main()
{
    vector<int> v1(10);
    for (int i = 0; i < v1.size(); i++)
    {
        v1[i] = i + 1;
    }

    //删除指定位置
    vector<int>::iterator it = v1.begin();
    it += 3;
    v1.erase(it);

    //distance(v1.begin(), it);

    //删除区间
    v1.erase(v1.begin(), v1.begin() + 3);

    for (vector<int>::iterator it = v1.begin(); it < v1.end(); it++)
    {
        if (*it == 5)
        {       
            printf("%x\n", it);
            vector<int>::iterator tmp = v1.erase(it); //注意以后开发中编译器版本问题
            printf("%x,%x\n",it,tmp);
        }
    }

    //插入
    v1.insert(v1.begin() + 2, 100);
    v1.insert(v1.end() - 1, 200);

    printVector(v1);

    system("pause");
}

3.队列deque

//双向队列
#include <deque>
void printDeque(deque<int>& q)
{
    for (int i = 0; i < q.size(); i++)
    {
        cout << q[i] << endl;
    }
}

void main()
{
    deque<int> d1;
    //添加到尾部
    d1.push_back(2);
    d1.push_back(10);
    //添加到头部
    d1.push_front(-90);
    d1.push_front(-30); 

    //printDeque(d1);

    //cout << d1.front() << endl;
    //cout << d1.back() << endl;

    //两个方向弹出
    //d1.pop_back();
    //d1.pop_front();

    printDeque(d1);

    //查找第一个-90元素索引位置，无需遍历
    deque<int>::iterator it = find(d1.begin(),d1.end(),-90);
    if (it != d1.end())
    {
        int idx = distance(d1.begin(), it);
        cout << "索引位置为：" << idx << endl;
    }


    system("pause");
}
//队列（没有迭代器）
/* void main() { queue<int> q; q.push(78); q.push(18); q.push(20); q.push(33); //q.front(); //q.back(); while (!q.empty()) { int tmp = q.front(); cout << tmp << endl; q.pop(); } system("pause"); } */

//优先级队列
/* #include <functional> void main() { //默认 最大值优先级 priority_queue<int> pq1; pq1.push(12); pq1.push(3); pq1.push(40); pq1.push(15); while (!pq1.empty()) { int tmp = pq1.top(); cout << tmp << endl; pq1.pop(); } cout << "----------" << endl; //最小值优先级队列 priority_queue<int, vector<int>,greater<int>> pq2; pq2.push(12); pq2.push(3); pq2.push(40); pq2.push(15); while (!pq2.empty()) { int tmp = pq2.top(); cout << tmp << endl; pq2.pop(); } system("pause"); } */

4.栈stack

//栈
/* #include <stack> void main() { stack<int> s; for (int i = 0; i < 10; i++) { s.push(i+1); } while (!s.empty()) { int tmp = s.top(); cout << tmp << endl; s.pop(); } system("pause"); } */

5.集合list,set,map

//list
#include <list>
void printList(list<int>& lst)
{
    //迭代器
    //没有重载“<”运算符
    for (list<int>::iterator it = lst.begin(); it != lst.end(); it++)
    {
        cout << *it << endl;
    }
}
//基本操作
/* void main() { list<int> lst; for (int i = 0; i < 10; i++) { //尾部插入元素 lst.push_back(i); } //头部插入元素 lst.push_front(80); lst.push_front(90); list<int>::iterator it = lst.begin(); it++; cout << *it << endl; //it = it + 3; 注意：不支持随机访问 printList(lst); system("pause"); } */


//删除
/* void main() { list<int> lst; for (int i = 0; i < 10; i++) { //尾部插入元素 lst.push_back(i); } list<int>::iterator it = lst.begin(); //删除 it++; //删除第二个元素 //lst.erase(it); //删除区间（已经被删除了元素不能再删除） list<int>::iterator it_begin = lst.begin(); list<int>::iterator it_end = lst.begin(); it_end++; it_end++; it_end++; lst.erase(it_begin, it_end); //直接根据内容删除元素 lst.remove(5); printList(lst); system("pause"); } */

//list插入（应用：频繁的修改）
//vector（应用：随机访问v[100]）
/* void main() { list<int> lst; for (int i = 0; i < 10; i++) { //尾部插入元素 lst.push_back(i); } list<int>::iterator it = lst.begin(); it++; lst.insert(it, 100); printList(lst); system("pause"); } */

//set 元素唯一 默认从小到大
#include <set>

void printSet(set<int> &s)
{
    for (set<int>::iterator it = s.begin(); it != s.end(); it++)
    {
        cout << *it << endl;
    }
}
/* void main() { set<int> s; //添加元素 for (int i = 0; i < 10; i++) { s.insert(i+1); } s.insert(20); s.insert(15); s.insert(15); //删除 set<int>::iterator it = s.begin(); it++; s.erase(it); printSet(s); system("pause"); } */

//元素按照从大到小排列
/* #include <functional> void main() { //同Java中：Map<String,List<String>> set<int,greater<int>> s; s.insert(10); s.insert(5); s.insert(20); s.insert(99); for (set<int,greater<int>>::iterator it = s.begin(); it != s.end(); it++) { cout << *it << endl; } system("pause"); } */

//元素类型为Teacher对象，按照年龄排序
/* class Teacher { public: Teacher(char* name, int age) { this->name = name; this->age = age; } void print() { cout << name << "," << age << endl; } public: char* name; int age; }; //自定义排序规则 //仿函数 struct MyAgeSorter { bool operator()(const Teacher &left, const Teacher &right) { return left.age < right.age; } }; void main() { set<Teacher, MyAgeSorter> s; s.insert(Teacher("jack",18)); s.insert(Teacher("rose", 20)); s.insert(Teacher("jason", 22)); s.insert(Teacher("alan", 5)); //s.insert(Teacher("jimy", 5)); //不会插入 for (set<Teacher>::iterator it = s.begin(); it != s.end(); it++) { cout << (*it).name << "," << (*it).age << endl; } system("pause"); } */

//set查找
/* void main() { set<int> s; //添加元素 for (int i = 0; i < 10; i++) { s.insert(i + 1); } //printSet(s); //等于4的元素指针 set<int>::iterator s_4 = s.lower_bound(4); //cout << *s_4 << endl; //大于4的元素指针 set<int>::iterator s_5 = s.upper_bound(4); //cout << *s_5 << endl; //一次性获取等于4的元素指针，和大于4的元素指针\ //BasicNameValuePair pair<set<int>::iterator, set<int>::iterator> p = s.equal_range(4); cout << *p.first << endl; cout << *p.second << endl; system("pause"); } */


//multiset 允许重复的元素
/* void main() { multiset<int> s; s.insert(2); s.insert(8); s.insert(2); s.insert(8); for (multiset<int>::iterator it = s.begin(); it != s.end(); it++) { cout << *it << endl; } system("pause"); } */


//map添加元素的方式
#include <map>
#include <string>
/* void main() { //key -> value //1. map<int, string> map1; map1.insert(pair<int, string>(1,"jack")); map1.insert(pair<int, string>(2, "rose")); //2 map1.insert(make_pair(3,"jason")); //3 map1.insert(map<int,string>::value_type(4,"alan")); //4 map1[5] = "jimmy"; //map["NO1"] = 90; //前三种方式，如果key已经存在，重复添加会报错 //第四种方式，如果key已经存在，重复添加会覆盖 //遍历输出 for (map<int, string>::iterator it = map1.begin(); it != map1.end(); it++) { cout << it->first << "," << it->second << endl; } system("pause"); } */

void printMap(map<int, string> &map1)
{
    for (map<int, string>::iterator it = map1.begin(); it != map1.end(); it++)
    {
        cout << it->first << "," << it->second << endl;
    }
}

//删除
/* void main() { map<int, string> map1; map1.insert(pair<int, string>(1, "jack")); map1.insert(pair<int, string>(2, "rose")); map1.insert(pair<int, string>(3, "jason")); map<int, string>::iterator it = map1.begin(); it++; map1.erase(it); printMap(map1); system("pause"); } */

//添加的结果
/* void main() { map<int, string> map1; map1.insert(pair<int, string>(1, "jack")); map1.insert(pair<int, string>(2, "rose")); map1.insert(pair<int, string>(3, "jason")); //获取添加的结果（first元素指针，second 是否成功） pair<map<int, string>::iterator, bool> res = map1.insert(pair<int, string>(3, "alan")); if (res.second) { cout << "添加成功" << endl; } else { cout << "添加失败" << endl; } printMap(map1); system("pause"); } */


//查找
/* void main() { map<int, string> map1; map1.insert(pair<int, string>(1, "jack")); map1.insert(pair<int, string>(2, "rose")); map1.insert(pair<int, string>(3, "jason")); printMap(map1); cout << "---------" << endl; //获取key等于大于5的元素的值 pair<map<int, string>::iterator, map<int, string>::iterator> p = map1.equal_range(2); if (p.first != map1.end()){ //等于2的元素key value cout << p.first->first << p.first->second << endl; //大于2的元素key value cout << p.second->first << p.second->second << endl; } system("pause"); } */

//一个key对应多个value
//一个部门多个员工
//multimap
/* class Employee { public: Employee(char* name,int age) { this->name = name; this->age = age; } public: char* name; int age; }; void main() { multimap<string, Employee> map1; //开发部 map1.insert(make_pair("开发", Employee("搁浅", 20))); map1.insert(make_pair("开发", Employee("彪哥", 20))); //财务 map1.insert(make_pair("财务", Employee("小颖", 16))); map1.insert(make_pair("财务", Employee("rose", 20))); //销售 map1.insert(make_pair("销售", Employee("阿呆", 30))); map1.insert(make_pair("销售", Employee("呵呵", 30))); //遍历输出 for (multimap<string, Employee>::iterator it = map1.begin(); it != map1.end(); it++) { cout << it->first << "," << it->second.name << "," << it->second.age << endl; } cout << "----------------" << endl; //只获取“财务”部的员工 //获取“财务部”员工的个数，key对应的value的个数 int num = map1.count("财务"); multimap<string, Employee>::iterator it = map1.find("财务"); int c = 0; //控制循环的次数 while (it != map1.end() && c < num) { cout << it->first << "," << it->second.name << "," << it->second.age << endl; it++; c++; } system("pause"); } */
//深拷贝与浅拷贝
/* class Employee { public: //构造函数 Employee(char* name, int age) { this->name = new char[strlen(name) + 1]; strcpy(this->name, name); this->age = age; } //析构函数 ~Employee() { if (this->name != NULL) { delete[] this->name; this->name = NULL; this->age = 0; } } //拷贝构造函数 //Employee e = Employee(const Employee &obj) { this->name = new char[strlen(obj.name) + 1]; strcpy(this->name, obj.name); this->age = obj.age; } //重载= //e1 = e2; Employee& operator=(const Employee &obj) { //释放旧的内存 if (this->name != NULL) { delete[] this->name; this->name = NULL; this->age = 0; } //重新分配 this->name = new char[strlen(obj.name) + 1]; strcpy(this->name, obj.name); this->age = obj.age; return *this; } public: char* name; int age; }; void func() { vector<Employee> v1; Employee e1("jack",20); v1.push_back(e1); } void main() { //vector<Employee> v1; //Employee e1("jack",20); //将e1拷贝到vector中 //v1.push_back(e1); func(); system("pause"); } */