ANSI C program problem with %s crashing program

[DougP]

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

int main(){
	
	printf("%s",strspn("Cows like to moo.","Ceiklosw "));
	return 0;
}

When I create a simple program to test said line the program crashes.
The problem appears to be %s. if I change it to be %c it runs, but returns nothing to the screen.
If however I run an example from the book which has a lot of %s in the program, it runs just fine. the samples as c files which I copy and paste. I need to know what's going wrong.
I am using C-Free editor and minGW compiler and the program compiles just fine but when running it gives error in a separate popup window
test.exe has encountered a problem and needs to close.
We are sorry for the inconvenience.
Since I also have VS 2005 loaded there is a debug button and a close button.

DougP
< I Built one

 

[ArkM]

The strspn function returns integer, not a pointer value. The %s format specification wants a pointer to char. Now printf treats an integer as a pointer and your program crashed.

To print an (unsigned in this case) integer use %u format specification.

And reread strspn specification...

 

[xwb]

Also #include <string.h>