getting segmentation fault in a small c program

Question

i wrote a small prog :

  1 #include<stdio.h>  
  2 main(){  
  3         char* str = "string";  
  4         *str = 'k';  
  5         printf("string is = %s
",str);
  6 }

This program gets compiled without any error or warnings, but when i run it, it gives segmentation fault. While if i rewrite the 3rd line as : char str[] = "string"; this program works perfectly fine. Can anyone please let me know what is the issue here ??? What is the difference between these two different ways of writing the 3rd line. Any help will be greatly appreciated. thanks.

Answer 1

char* str = "string";

This puts the string in read-only memory. It is undefined behavior (usually unpleasant behavior) when you try to modify it with the next line. Try something like

char str[] = "string";

instead.