#include <stdio.h>

int str_len(char *s)
{
	char *p = s;

	while (*p != '\0')
		p++;
	return p - s;
}

main()
{
	char s[] = "hello, world\n";

	printf("hello, world: %d ( 12 + '\\0')\n", str_len( s ));

	exit(0);
}