ref: 4eaac6bfb11cc84259e8b418d4babffdf1c637eb
dir: /lib/c/string/strspn.c/
#include <string.h> #undef strspn size_t strspn(const char *s1, const char *s2) { const unsigned char *s = s1; const unsigned char *accept = s2; unsigned ch; size_t n; char buf[__NUMCHARS]; memset(buf, 0, sizeof(buf)); while (ch = *accept++) buf[ch] = 1; for (n = 0; (ch = *s++) && buf[ch]; ++n) ; return n; }