replace()用法
#include<iostream>
#include<string>
using namespace std;
int main()
{
string str = "abcdef";
str.replace(0,3,"XXX");
cout << str << endl; //输出: XXXdef
str.replace(0, 3, 3, 'Y');
cout << str << endl; //输出: YYYdef
string s = "2020";
str.replace(0, 3, s, 0, 3);
cout << str << endl; //输出: 202def
return 0;
}
