帮我看看这个例子，怎么错了

#include <iostream>
using namespace std;
#include<string>

int main()
{
    string str;
    char s[] = "12345";

    str.reserve(5);

    for (int i = 0; i < 5; i++)
        str[i] = s[i];

    cout << "str:" << str << endl;
    cout << "length():" << str.length() << endl;
    system("pause");
    return 0 ;
}
 

[此贴子已经被作者于2021-8-16 11:23编辑过]