C++PRIMER第十章课后练习

10.1

#include
#include
#include
using namespace std;
int main()
{
vector vec{ 1,1,1,1,2,2,2 };
int n=count(vec.begin(), vec.end(), 1);
cout << n << endl;
return 0;
}

10.2

#include
#include
#include
using namespace std;
int main()
{
list li{ "aa","aa","bb","bb","bb" };
int n = count(li.begin(), li.end(), "aa");
cout << n << endl;
return 0;
}

10.3

#include
#include
#include
using namespace std;
int main()
{
vector a;
for(int i = 0; i < 10; ++i)
{
a.push_back(i);
}
int sum = accumulate(a.begin(), a.end(), 0);
cout << sum;
return 0;
}

10.4

合法,但是初始值应该为0.0,否则会截断数据

10.5

出错,const char*不支持==来比较

10.6

#include
#include
#include
using namespace std;
int main()
{
vector a;
for(int i = 0; i < 10; ++i)
{
a.push_back(i);
}
fill_n(a.begin(), 10, 0);
for (int i : a)
cout << i << " ";
return 0;
}

10.7

a)错误,vec为空.最后一句改为

copy(lst.cbegin(),lst.end(),back_inserter(vec));

b)错误,reserve不影响容器里保存的元素数量,只是预先分配内存空间,vec依旧为空;

同上题一样改为插入迭代器

10.8

因为改变容器的大小是back_inserter,并非标准库算法

10.9

#include
#include
#include
#include
using namespace std;
void elimDups(vector& v)
{
string word;
cout << "输入10个单词:\n";
for (int i = 0; i < 10; ++i)
{
cin >> word;
v.push_back(word);
}
auto unique_end=unique(v.begin(), v.end());
v.erase(unique_end, v.end());
cout << "调整后的vector:\n";
for (string s : v)
cout << s << " ";
}
int main()
{
vector vec;
elimDups(vec);
return 0;
}

10.10

因为算法是对迭代器进行操作,而非容器.

10.11

#include
#include
#include
#include
using namespace std;
bool isShorter(const string&s1, const string&s2)
{
return s1.size() < s2.size();
}
void elimDups(vector& v)
{
string word;
cout << "输入10个单词:\n";
for (int i = 0; i < 10; ++i)
{
cin >> word;
v.push_back(word);
}
sort(v.begin(), v.end());
auto unique_end=unique(v.begin(), v.end());
v.erase(unique_end, v.end());
stable_sort(v.begin(), v.end(), isShorter);
cout << "调整后的vector:\n";
for (string s : v)
cout << s << " ";
}


int main()
{
vector vec;
elimDups(vec);
return 0;
}

10.12

bool compare(const Sales_date&sd1, const Sales_date&sd2)
{
return sd1.isbn() < sd2.isbn();
}
void compareIsbn(vector &vecs)
{
sort(vecs.begin(), vecs.end(), compare);
}

10.13

#include
#include
#include
#include
using namespace std;
bool biger5(const string&s)
{
return s.size() >= 5;
}


int main()
{
vector vec{"aa","1234","d","12345","e","111222","223344"};
auto part_end = partition(vec.begin(), vec.end(), biger5);
for (auto beg = vec.begin(); beg != part_end; ++beg)
cout << *beg << " ";
return 0;
}

10.14

[](const int&x,const int&y){return x+y;}

10.15

[x](const int y){return x+y;}

10.17

void compareIsbn(vector &vecs)
{
sort(vecs.begin(), vecs.end(), [](const Sales_date &sd1,const Sales_date &sd2,){return sd1.isbn() }

10.18

#include
#include
#include
#include
using namespace std;


void biggis(vector &words, vector::size_type sz)
{
sort(words.begin(), words.end());                    //字典排序
auto unique_end = unique(words.begin(), words.end());//重复单词排序
words.erase(unique_end, words.end());//删除多余元素
stable_sort(words.begin(), words.end(), 
[](const string&s1,const string&s2) {return s1.size() < s2.size(); });//按长度重新排序,长度相同的相对顺序保持不变
for_each(words.begin(), words.end(), [](const string&s) {cout << s << " "; });
cout << endl;
auto end_part = partition(words.begin(), words.end(),
[sz](const string&s) {return s.size() >= sz; });
for_each(words.begin(), end_part, [](const string&s) {cout << s << " "; });
}
int main()
{
vector vec{ "aa","a","bb","ab","ab","a","ccc","caa","caa" };
biggis(vec, 2);
return 0;
}

10.19

#include
#include
#include
#include
using namespace std;


void biggis(vector &words, vector::size_type sz)
{
sort(words.begin(), words.end());                    //字典排序
auto unique_end = unique(words.begin(), words.end());//重复单词排序
words.erase(unique_end, words.end());//删除多余元素
cout << "划分前:\n";
for_each(words.begin(), words.end(), [](const string&s) {cout << s << " "; });
cout << endl;
auto end_part = stable_partition(words.begin(), words.end(),
[sz](const string&s) {return s.size() >= sz; });


cout << "划分后:\n";
for_each(words.begin(), end_part, [](const string&s) {cout << s << " "; });
}
int main()
{
vector vec{ "aa","a","bb","ab","ab","a","ccc","caa","caa" };
biggis(vec, 2);
return 0;
}

10.20

#include
#include
#include
#include
using namespace std;
int main()
{
vector vec{ "aa","a","bb","ab","ab","a","ccc","caa","caa" ,"1234567"};
size_t n = count_if(vec.begin(), vec.end(), [](const string&s) {return s.size() > 6; });
cout << n;
return 0;
}

10.21

#include
#include
#include
#include
using namespace std;
int main()
{
int n;
cin >> n;
auto f = [&n]()->bool 
{if (n)
{
--n; return false;
}
else 
return true; };
while (n)
cout << f() << endl;
cout << f();
return 0;
}

10.22

#include
#include
#include
#include
#include
using namespace std;
bool shorter6(const string&s, string::size_type n)
{
return s.size() <= n;
}
int main()
{
vector vec{ "aa","1234","d","12345","e","111222","11223344" };
int n=count_if(vec.begin(), vec.end(), bind(shorter6, placeholders::_1, 6));
cout << n;
return 0;
}

10.23

1个函数名称+N个参数(该函数具有的参数)

10.24

#include
#include
#include
#include
#include
using namespace std;
bool check_size(const string&s, string::size_type sz)
{
return s.size() < sz;
}
int main()
{
const string s("hehe");
vector vec{ 1,2,3,4,5,6,7,8,9 };
cout<<*find_if(vec.begin(), vec.end(), bind(check_size, s, placeholders::_1));
return 0;
}

10.25

#include
#include
#include
#include
#include
using namespace std;
bool check_size(const string&s, string::size_type n)
{
return s.size() > n;
}
bool isShorter(const string&s1, const string&s2)
{
return s1.size() < s2.size();
}
ostream& print(ostream&os, const string&s,char c)
{
return os << s << c;
}
void biggis(vector &words, vector::size_type sz)
{
sort(words.begin(), words.end());                    //字典排序
auto unique_end = unique(words.begin(), words.end());//重复单词排序
words.erase(unique_end, words.end());//删除多余元素
stable_sort(words.begin(), words.end(),
bind(isShorter,placeholders::_1,placeholders::_2));//按长度重新排序,长度相同的相对顺序保持不变
for_each(words.begin(), words.end(), bind(print, ref(cout), placeholders::_1, ' '));
cout << endl;
auto end_part = partition(words.begin(), words.end(),
bind(check_size, placeholders::_1, sz));
for_each(words.begin(), end_part, bind(print,ref(cout),placeholders::_1,' '));
}
int main()
{
vector vec{ "aa","a","bb","ab","ab","a","ccc","caa","caa" };
biggis(vec, 2);
return 0;
}

10.27

#include
#include
#include
#include
#include
using namespace std;
int main()
{
vector vec{ 1,1,2,2,3,3,4,5,6,7,7,8,9 ,1,1 };
list li;
unique_copy(vec.begin(), vec.end(), back_inserter(li));
for (int i : li)
cout << i << ",";
return 0;
}

10.28

#include
#include
#include
#include
#include
using namespace std;
int main()
{
vector vec{ 1,2,3,4,5,6,7,8,9 };
list li[3];
copy(vec.begin(), vec.end(), inserter(li[0],li[0].begin()));
copy(vec.begin(), vec.end(), back_inserter(li[1]));
copy(vec.begin(), vec.end(), front_inserter(li[2]));
for (list& l : li)
{
for (int i : l)
cout << i << ",";
cout << endl;
}
return 0;
}

10.29

#include
#include
#include
#include
#include
using namespace std;
int main()
{
ofstream fout("file.txt");
istream_iterator ins(cin), eof;
ostream_iterator outs(fout, " ");
copy(ins, eof, outs);
fout.close();
ifstream fin("file.txt");
istream_iterator fins(fin),eofs;
vector vec;
while (fins != eof)
vec.push_back(*fins++);
ostream_iterator out_iter(cout, ",");
cout << "vector中的数据为:\n";
copy(vec.begin(), vec.end(), out_iter);
return 0;
}

10.30

#include
#include
#include
#include
using namespace std;
int main()
{
istream_iterator in_iter(cin), eof;
ostream_iterator out_iter(cout, ",");
vector vec(in_iter,eof);
sort(vec.begin(), vec.end());
copy(vec.begin(),vec.end(), out_iter);
return 0;
}

10.31

#include
#include
#include
#include
using namespace std;
int main()
{
istream_iterator in_iter(cin), eof;
ostream_iterator out_iter(cout, ",");
vector vec(in_iter,eof);
sort(vec.begin(), vec.end());
unique_copy(vec.begin(),vec.end(), out_iter);
return 0;
}

10.33

#include
#include
#include
using namespace std;
void test(const char* inc, const char*ouc1, const char*ouc2)
{
ifstream fin(inc);
ofstream  fout1(ouc1), fout2(ouc2);
istream_iterator in_iter(fin),eof;
ostream_iterator out1_iter(fout1, " "), out2_iter(fout2, "\n");
while (in_iter != eof)
{
if (*in_iter % 2)
*out1_iter++ = *in_iter++;
else
*out2_iter = *in_iter++;
}
}


int main()
{
test("file.txt", "奇数.txt", "偶数.txt");
return 0;
}

10.34

#include
#include
using namespace std;
int main(int argc,char*argv[])
{
vector vec{ 1,2,3,4,5,6,7,8,9 };
for (auto iter = vec.rbegin(); iter != vec.rend(); ++iter)
cout << *iter << ",";
return 0;
}

10.35

#include
#include
using namespace std;
int main(int argc,char*argv[])
{
vector vec{ 1,2,3,4,5,6,7,8,9 };
auto iter = vec.end();
while (iter != vec.begin())
{
cout << *--iter << ",";
}
return 0;
}

10.36

#include
#include
#include
using namespace std;
int main(int argc,char*argv[])
{
list li{ 0,1,0,2,0,3,0 ,4 };
auto it= find(li.crbegin(), li.crend(), 0);
cout << "下标:" << 7-distance(li.crbegin(),it)<< endl;
}

10.37

#include
#include
#include
#include
#include
using namespace std;
int main(int argc,char*argv[])
{
vector vec{ 1,2,3,4,5,6,7,8,9,10 };
list li;
copy(vec.crbegin() + 3, vec.crbegin() + 8, back_inserter(li));
for (int i : li)
cout << i << ",";
return 0;
}

10.38

输入,输出,前向,双向,随机迭代器

10.39

list上的迭代器属于双向迭代器,vector属于随机访问迭代器 

10.40

copy的前两个参数要求前向迭代器,第3个参数要求输出迭代器;

reverse要求双向迭代器,

unique要求前向迭代器

10.41

a)将迭代器范围内的old_val替换为new_val

b)将满足pred为true的元素替换为new_val

c)将迭代器范围内的元素拷贝到dest中,其中值为old_val的元素替换为new_val

d)将迭代器范围内的元素拷贝到dest中,其中满足pred为true的元素替换为new_val

10.42

#include
#include
#include
#include
using namespace std;
void elimDups(list& li)
{
string word;
cout << "输入10个单词:\n";
for (int i = 0; i < 10; ++i)
{
cin >> word;
li.push_back(word);
}
li.sort();
li.unique();
cout << "调整后的vector:\n";
for (string s : li)
cout << s << " ";
}
int main()
{
list lis;
elimDups(lis);
return 0;
}