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string类的构造函数

构造函数程序示例：

#include 
   
    #include 
    
     int main(){  using namespace std;  string one("Lottery Winner!");  cout << one << endl;  string two(20, '$');  cout << two << endl;  string three(one);  cout << three << endl;  one += " Oops!";  cout << one << endl;  two = "Sorry! That was ";  three[0] = 'P';  string four;  four = two + three;  cout << four << endl;  char alls[] = "All's well that ends well";  string five(alls, 20);  cout << five << "!\n";  string six(alls + 6, alls + 10);  cout << six << ", ";  string seven(&five[6], &five[10]);  cout << seven << "...\n";  string eight(four, 7, 16);  cout << eight << " in motion!" << endl;  return 0;}
    
   

string类输入：

C-风格的字符串输入：

char info[100];

cin >> info;

cin.getline(info, 100);

cin.get(info, 100);

对于string对象：

string stuff;

cin >> stuff;

getline(cin, stuff);

指定边界：

c-string: cin.getline(info, 100, ':');

getline(stuff, ':')

string的getline自动调整大小。而c-风格的不行

string对象的最大长度是由string::npos指定的，通常是unsigned int值

string的 operator>>()

文件读取示例：

#include 
   
    #include 
    
     #include 
     
      #include 
      
       int main(){  using namespace std;  ifstream fin;  fin.open("tobuy.txt");  if (fin.is_open() == false)  {    cerr << "Can't open file. Bye.\n";    exit(EXIT_FAILURE);  }  string item;  int count = 0;  getline(fin, item, ':');  while (fin)  {    ++count;    cout << count << ": " << item << endl;    getline(fin, item, ':');  }  cout << "Done\n";  fin.close();  return 0;}
      
     
    
   

tobuy.txt：

sardines:chocolate ice cream:pop corn:leeks:cottage cheese:olive oil:butter:tofu:

输出结果

先完结

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