problem with getting correct string length

I am having some trouble getting my program to make arrays of the right length. Our assignment is to make functions called "category1", "category2" and so on, all of which analyzes a char array and determines if the passed char array is in the specific category.
The "category" that I am having trouble with determines if the first third of the char array appears elsewhere in the whole array. Here's my code so far.

Code:

int Category4 (char s1[])
{
   int ndx, ndx2;
   char comp[strlen(s1)/3];

   for (ndx = 0; ndx < strlen(comp); ndx++) {
      comp[ndx] = s1[ndx];
   }

   for (ndx = strlen(comp); ndx < strlen(s1); ndx++) {
      if (s1[ndx] == comp[0]) {
         for (ndx2 = 0; ndx2 < strlen(comp); ndx2++) {
            if (comp[ndx2] != s1[ndx+ndx2]) {
               break;
            }
            if (ndx2 == strlen(comp)) {
               printf("%s is in category 4.\n", s1);
               return 1;
            }
         }
      }
   }

   return 0;
}

I pass a 6 character string each time, and the length that I get for the array I created in the function (comp) comes out to 5. Does anyone know why this is happening?

You can't use string functions if you aren't actually dealing with strings. You have to have a null character on the end of each for it to be considered a string. Say you pass an array of six characters, and it's really a string, so it's actually got seven characters total, just for the sake of argument:

Code:

void foo( char bar[] )
{
    char baz[ strlen(  bar ) = 6, 6 / 3 = 2, baz = 2 ];
    ... now assume you actually make 'baz' a string ...
    ... that leaves you 1 usable character ...

    for( x = 0; x < strlen baz = 1; x++ )
        ... whatever you're doing here is only going to happen to 1 character, so you don't need a loop ...

}

Start looking at that, and see if that's really what you had in mind.


Quzah.