strspn - Returns the index of the first character in str1 that does not match any of the characters in str2 in C

1. Forget Code
2. C
3. strspn - Returns the index of the first character in str1 that does not match any of the characters in str2

  #include <string.h>
  #include <stdio.h>
  int main(void)
  {
    int len;

    len = strspn("this is a test", "hi");
    printf("%d", len);

    return 0;
  }