Question

Here I am trying to swap two characters in a string using XOR operation. But GCC compiler throws me a segmentation fault.

#include <stdio.h>
#include <stdlib.h>

int main()
{
    char *str = "welcome";

    str[0] = str[0] ^ str[1];  // Segmenation fault here
    str[1] = str[0] ^ str[1];
    str[0] = str[1] ^ str[0]; 

    printf("%s", str);
    return 0;
}

Answer 1

You can’t change literals in C. str points to read-only memory.

Try instead:

char str[] = "welcome";

There is a C FAQ on the subject.