string.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/lib/string.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <string.h>

size_t strspn(const char *s, const char *accept)
{
	const char *p;
	const char *a;
	size_t count = 0;

	for (p = s; *p != '\0'; ++p) {
		for (a = accept; *a != '\0'; ++a) {
			if (*p == *a)
				break;
		}
		if (*a == '\0')
			return count;
		++count;
	}
	return count;
}

size_t strcspn(const char *s, const char *reject)
{
	const char *p;
	const char *r;
	size_t count = 0;

	for (p = s; *p != '\0'; ++p) {
		for (r = reject; *r != '\0'; ++r) {
			if (*p == *r)
				return count;
		}
		++count;
	}
	return count;
}

size_t strlen(const char *s)
{
	const char *sc;

	for (sc = s; *sc != '\0'; ++sc)
		/* nothing */;
	return sc - s;
}

char *strchr(const char *s, int c)
{
	for (; *s != (char)c; ++s)
		if (*s == '\0')
			return NULL;
	return (char *)s;
}