c/c++ 标准库 string

标准库 string的小例子
test1~test10

#include <iostream>using namespace std;int main(void){//test1                                                                      //string s1,s2;                                                              //cin >> s1 >> s2;                                                           //cout << s1 << ";" << s2 << endl;                                           //test2                                                                      //string wd;                                                                 //while(cin >> wd){                                                          //  cout << wd << endl;                                                      //}                                                                          //test3                                                                      /*                                                                           string line;                                                                 while(getline(cin, line)){                                                   cout << line << endl;     }                                                                            *///test4                                                                      /*                                                                           string line;                                                                 while(getline(cin, line)){                                                   if(!line.empty()){                                                         cout << line << endl;                                                    }                                                                          else{                                                                      cout << "empty" << endl;                                                 }                                                                          }                                                                            *///test5                                                                      /*                                                                           string line;                                                                 while(getline(cin, line)){                                                   if(line.size() > 2){                                                       cout << line << endl;                                                    }                                                                          }        string::size_type len = string("1111111111111111abc").size();                cout << len << endl;                                                         int n = -1;                //注意，如果n为负值，不管 len为多大的字符串，下面的条件都是真。//因为，编译器会把负值n转化为一个特别大的正数。if(len < n){                                                                 cout << "in" << endl;                                                      }                                                                            *///test6                                                                      /*                                                                           string s("asdfdsf!!!");                                                      decltype(s.size()) cnt = 0;                                                  for(auto c : s){                                                             if(ispunct(c))                                                             ++cnt;                                                                   }                                                                            cout << cnt << "times" << endl;                                              *///test7                                                                      /*                                                                           string s("aaasd!!!");                                                        for(auto& c : s){                                                            c = toupper(c);                                                            }                                                                            cout << s << endl;                                                           *///test8                                                                      /*                                                                           string s("abc def");                                                         if(!s.empty())                                                               s[0] = toupper(s[0]);                                                      cout << s << endl;                                                           *///test9                                                                      /*                                                                           string s("one two");                                                         for(decltype(s.size()) idx = 0;                                              idx != s.size() && !isspace(s[idx]); ++idx){                             s[idx] = toupper(s[idx]);                                                  }                                                                            cout << s << endl;                                                           *///test10                                                                     const string hex("0123456789ABCDEF");string result;string::size_type n;while(cin >> n){if(n < hex.size()){result += hex[n];}}cout << result << endl;}