C Tutorial/string.h/strcspn
strcspn
Item Value Header file string.h Declaration size_t strcspn(const char *str1, const char *str2); Return returns the index of the first character in *str1 that matches any of the characters in *str2.
<source lang="cpp">#include <string.h>
#include <stdio.h> int main(void) { int len; len = strcspn("this is a test", "ab"); printf("%d", len); return 0; }</source>