/* strnlen.c */
#include <stdio.h>

int stringlength(char *string_in);

int main()
{
  char mystring[] = "This is my string";

  printf("The length of the string is %d characters long.\n", 
    stringlength(mystring));
  return 0;
}

int stringlength(char *string_in)
{
  int countlength = 0;

  while(string_in[countlength] != '\0')
    countlength++;

  return(countlength);
}