技術標籤：C++string賦值操作

1.string中的賦值操作大致有以下幾種型別：

1. string &operator=(const char *s); //char*型別的字串 賦值給當前的字串
2. string &operator=(const string &s); //把字串s賦值給當前的字串
3. string &operator=(char c); //字元賦值給當前的字串
4. string &assign(const char *s); //把字串s賦值給當前的字串
5. string &assign(const char *s,int n); //把字元中的前n個字元賦值給當前的字串
6. string &assign(const string &s); //把字串s賦值給當前字串
7. string &assign(int n, char c); //用n個字元賦值給當前字串

   #include<iostream>
   #include<string>
   using namespace std;
   
   void test1()
   {
   	string s1;  //char*型別的字串 賦值給當前的字串
   	s1="hello world"; 
   	cout<<"s1 = "<<s1<<endl;
   	
   	string s2; //把字串s賦值給當前的字串
   	s2=s1; 
   	cout<<"s2 = "<<s2<<endl;
   	
   	string s3;  //字元賦值給當前的字串
   	s3='a';
   	cout<<"s3 = "<<s3<<endl; 
   	
   	string s4;  //把字串s賦值給當前的字串
   	s4.assign("hello world");
   	cout<<"s4 = "<<s4<<endl;
   	
   	string s5,s5_1;  //把字元中的前n個字元賦值給當前的字
   	s5.assign("hello world",5); 
   //	s5_1.assign(s1,5); 這種方式會報錯 
   	cout<<"s5 = "<<s5<<endl;
   	
   	string s6;//把字串s賦值給當前字串
   	s6.assign(s5);
   	cout<<"s6 = "<<s6<<endl;
   	
   	string s7;  //用n個字元賦值給當前字串
   	s7.assign(3,'a');
   	cout<<"s7 = "<<s7<<endl;
   }
   int main()
   {
   	test1();
   	return 0;
    }