Simple pointer question

Code:

main() {

char *s = "IDIOT";
char *start, *end;
start = s;
end = s+strlen(s)-1;
printf("%c, %c",*start, *end);      // prints   I   T
*start = *end;                            // crashing at this point
printf("%c, %c",*start, *end);     // should print T   T

}

What I'm trying to do above is just replace I with T and I'm getting a segmentation fault!!! am clueless, please can someone help!!!

 

In many modern OSs a string generated such as you have generated it lies in protected memory space. That means you can read it, but not write it. You can put it in local, writable space, if you like:

Code:

char writableString [] = "IDIOT";
char *start = writableString;
...etc., etc.