sprintf crashes but it is unclear why

Question

I tried the following code with sprintf, but it crashes in some cases and works fine in the other. Could anyone explain it to me?

#include <stdio.h>
#include <stdlib.h>
int main()
{
       //char *s = malloc(20); //works fine
       //char *s = "";         //does not work, no matter what the initial value is
       char s[20];       //works fine
       sprintf(s, "%s", "hello world");
       printf("%s",s);
       return 0;
}

score 3 · Accepted Answer · edited May 23 '17 at 12:07

When you are doing this:

char *s = "";

or

char *s = "longer string";

You are creating a literal string which is possibly placed in read-only memory. So you cannot change it later.

If you try to do the following syntax:

char s[] = "...";

the array will be initialized with the literal string and you will be able to modify the original array later.

sprintf crashes but it is unclear why

1 Answers1