I have the simple function below which swap two characters of an array of characters (s). However, I am getting a "Unhandled exception at 0x01151cd7 in Bla.exe: 0xC0000005: Access violation writing location 0x011557a4." error. The two indexes (left and right) are within the limit of the array. What am I doing wrong?

void swap(char* s, int left, int right) {
    char tmp = s[left];
    s[left] = s[right];
    s[right] = tmp;
}

swap("ABC", 0, 1);

I am using VS2010 with unmanaged C/C++. Thanks!