C++对C的改进和拓展\string类型

#include <iostream>
#include <string>
using namespace std;
 
int main()
{
  string s1;
  string s2 = "Student";
  string s3 = s2;
  string s4(8, 'A');  //8个A
  
  cout << "input >>";
  cin >> s1;  //遇到空格、tab、回车结束
  //带空格 >>> getline(cin,s1)
  cout << s1 << endl << s2 << endl << s3 << endl << s4 << endl;
  s4 = s1;
 
  cout << "s4=" << s4 << " length is>>" << s4.length() << endl;
  //length() 是 string 类的一个成员函数
 
  s2 = s3 + ' ' + s4;
  //右边可以是 string 字符串、C风格字符串、或一个 char 字符
  cout << "s2=" << s2 << endl;
 
  //对字符串进行操作
  s3.insert(7, "&Teacher"); //s3 7下标开始(不包括) 插入
  cout << "s3=" << s3 << endl;
 
  s3.replace(2, 4, "ar"); //s3 2下标开始(不包括) 长度为4的子串 替换
  cout << "s3=" << s3 << endl;
 
  s1 = s3.substr(6, 7); //s3 6下标开始(不包括) 长度为7字串
  cout << "s1=" << s1 << endl;
 
  int pos = s3.find("s1");  //s3中找s1，存在则返回 首字符下标,否则返回-1
  cout << "pos=" << pos << endl;
 
  s3.erase(5, 8); //5下标开始(不包括) 长度8
  cout << "s3=" << s3 << endl;
 
  bool f = s1 > s4;
  cout << "f=" << f << " boolalpha>>" << boolalpha << f << endl;
 
  return 0;
}