shithub: plan9front

ref: 0d59a2358a2a1f93fb28cd7f47f8420fbf06a9af
dir: /sys/src/libc/port/strcspn.c/

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#include <u.h>
#include <libc.h>

#define	N	256

long
strcspn(char *s, char *b)
{
	char map[N], *os;

	memset(map, 0, N);
	for(;;) {
		map[*(uchar*)b] = 1;
		if(*b++ == 0)
			break;
	}
	os = s;
	while(map[*(uchar*)s++] == 0)
		;
	return s - os - 1;
}