ref: 461cca7fa3f4225b2aa9bbba5c4690cd90fa7513
dir: /lib/c/src/strcspn.c/
#include <string.h> #undef strcspn size_t strcspn(const char *s1, const char *s2) { size_t n; int c; const char *p; for (n = 0; c = *s1++; ++n) { for (p = s2; *p && *p != c; ++p) /* nothing */; if (*p == c) break; } return n; }