[SOLVED] What should happen, when we try to modify a string constant?

What should happen, when we try to modify a string constant?

#include<stdio.h>
#include<string.h>

int main()
{
    int i, n;
    char *x="Alice"; // ....... 1
    n = strlen(x);   // ....... 2
    *x = x[n];       // ....... 3
    for(i=0; i<=n; i++)
    {
        printf("%s ", x);
        x++;
    }
    printf("\n");
    return 0;
}

String constant cannot be modified. In the above code *x means 'A'. In line 3 we are trying to modify a string constant. Is it correct to write that statement? When I run this code on Linux, I got segmentation fault. But on www.indiabix.com, they have given answer:

If you compile and execute this program in windows platform with Turbo C, it will give lice ice ce e It may give different output in other platforms (depends upon compiler and machine). The online C compiler given in this site will give Alice lice ice ce e as output (it runs on Linux platform).

Solution

Your analysis is correct. The line

*x = x[n];

is trying to modify a string literal, so it's undefined behavior.

BTW, I checked the website that you linked. Just browsing it for two minutes, I've already found multiple incorrect code samples (to name a few, using gets, using char(not int) to assign return value of getchar, etc), so my suggestion is don't use it.