/* strspn function */
#include <string.h>

size_t (strspn)(const char *s1, const char *s2)
	{	/* find index of first s1[i] that matches no s2[] */
	const char *sc1, *sc2;

	for (sc1 = s1; *sc1 != '\0'; ++sc1)
		for (sc2 = s2; ; ++sc2)
			if (*sc2 == '\0')
				return (sc1 - s1);
			else if (*sc1 == *sc2)
				break;
	return (sc1 - s1);	/* null doesn't match */
	}

