Exer03_11.cpp

// Warning: This is for verification. It CANNOT be compiled successfully by every compiler.
// The problem lies in line 17.
#include <iostream>
#include <string>
using std::cout;
using std::cin;
using std::endl;
using std::string;
int main()
{
    const string s = "Keep out!";
    // Type of c is const reference(or more precisely, reference to const).
    // If no operation in range for is to change value of s, it's okay, or it's an error.
    for(auto &c : s)
    {
        cout << c; // okay
        c = 'X'; // error, cannot compile successfully
    }
    cout << endl;
    return 0;
}
// ******compile info under cl******
// Exer03_11.cpp
// Exer03_11.cpp(17) : error C3892: “c”: 不能给常量赋值

// ******compile info under g++******
// Exer03_11.cpp: In function 'int main()':
// Exer03_11.cpp:17:5: error: assignment of read-only reference 'c'
//    c = 'X'; // error, cannot compile successfully
//      ^