Thread: Comparing string arrays

I'm trying to get my program to store only letters in two arrays. So far I have:

Code:

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

main () {

   printf("Enter something: ");
   char temp[100];

   fgets(temp, 100, stdin);

   int c;
   int letters = 0;
   for (c = 0; c <= strlen(temp); c++) {
      if (isalpha(temp[c])) {
         letters++;
           }
         }

   int *ptr;
   ptr = &letters;
   char str[*ptr];
   char rev[*ptr];
   printf("Letters amount: %d\n", *ptr);

   int i;
   int k = 0;
   for (i = 0; i < strlen(temp); i++) {
   if (isalpha(temp[i])) {
         str[k] = temp[i];
         k++;
           }
        }

   k = 0;
   for(i = strlen(str)-1; i >= 0; i--){

        rev[k] = str[i];
      k++;
    }



   printf("You entered: %s\n", str);
   printf("The reverse: %s\n", rev);

}

If I put "Test":
You entered: Test
The reverse: tseT

If I put "Testing One Two Three":
You entered: TestingOneTwoThree
The reverse: eerhTowTenOgnitseT@

If I put "Testinggg":
You entered: Testingggggaj<@
The reverse: @<jagggggnitseT

I have to get str[] and rev[] to store only letters because I will have to compare them later.

I understand that it has something to do with the null-byte terminator in arrays, so how can I adjust my code so that it stores the letters correctly?