代码：
#include<iostream>
using namespace::std;
int main(void)
{
string str("abcdefg");
cout << str << endl;
cout << str.c_str() << endl;
cout << str[0] << endl;
cout << str[2] << endl;
cout << str[23] << endl; //over
cout << str.at(3) << endl;
//cout << str.at(23) << endl; //over
try //solve over
{
str.at(23);
}
catch(...)
{
cout << "over" << endl;
}
return 0;
}
运行结果：