/* string functions */
#include <string.h>

char *strchr(const char *s, int c)
{	/* find first occurrence of c in char s[] */
	const char ch = c;

	for (; *s != ch; ++s)
		if (*s == '\0')
			return (NULL);
	return ((char *) s);
}

size_t strlen(const char *s)
{	/* find length of s[] */
	const char *sc;

	for (sc = s; *sc != '\0'; ++sc);
	return (sc - s);
}

void *memcpy(void *s1, const void *s2, size_t n)
{	/* copy char s2[n] to s1[n] in any order */
	char *su1;
	const char *su2;

	for (su1 = s1, su2 = s2; 0 < n; ++su1, ++su2, --n)
		*su1 = *su2;
	return (s1);
}