源程序：
#include <iostream>
#include <string>
using namespace std;
int main()
{
string s1, s2;
s1 = "c++程序";
s2 = s1;
string s3;
cout << "s3=" << s3 << endl;
s3 = s1 + s2;
cout << s1 + s2 << endl;
cout << "s3=" << s3 << endl;
bool b = s1 < s3;
cout << "bool=" << b << endl;
char c = s1[2];
cout << "c=" << c << endl;
cout << s1[2] << endl;
char arrstr[] = "Hello";
s3 = s1 + arrstr;
cout << s3 << endl;
system("pause");
}
运行结果：
