strspn example in C

 Header file:

    string.h

Synopsis:

   size_t strspn(char *str, char *search_str);

Description:

    It returns the length of the prefix of str which consists of characters in string search_str.

strspn function C example:

  #include<stdio.h>
  #include<string.h>
  #include<stdlib.h>

  int main () {
        char input1[100];
        int ret;

        printf("Enter a string:");
        fgets(input1, 90, stdin);

        ret = strspn(input1, "abcdefghijklnmopqrstuvwxyz");
        printf("Return value: %d\n", ret);
        return 0;
  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter a string:hello world
  Return value: 5

Here, "hello world" is the input string.  And we don't have space in search_str ("abcdefghijklmnopqrstuvwxyz").  So, the number of characters in input string("hello world") that are present before space is returned as return value.  In our case, there are 5 characters before space("hello") and the same value is returned as return value.