C: string length function

Added test driver for strlen function which comes from K&R C.

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

int strlen1(char s[]);
/* test strlen function */
main()
{
   char text[]="The power of C!" ;
   printf("The string: %s\n",text);
   printf("The length of string is %d - using strlen()\n", strlen(text));
   printf("The length of string is %d - using strlen1()\n", strlen1(text)) ;
   return 0;
}
/* strlen:  return length of s */
int strlen1(char s[])
{
   int i=0;
   while (s[i] != '\0')
       ++i;
   return i;
}

test result:

$ strlen1
The string: The power of C!
The length of string is 15 - using strlen()
The length of string is 15 - using strlen1()