#include <stdio.h>
size_t strcspn_(const char* s1, const char* s2) {
// find index in s1 of first s2[i] in s1
const char* p1, * p2;
for (p1 = s1; *p1 != '\0'; p1++)
for (p2 = s2; *p2 != '\0'; p2++)
if (*p1 == *p2) // *p2 = "am" *p1 = "ammin"
return p1 - s1;
return p1 - s1;
}
int main() {
const char str1[32] = "c programming";
const char str2[32] = "am";
printf("%zu", strcspn_(str1, str2));
return 0;
}
/*
run:
7
*/