Thread: Feedback on recursive function

The recursive function is bolded, i got feedback and was told that the static variable made the function seem a lot like a iterative function but he did not say why. Can someone explain it to me?

Code:

#define MAX 100
#include <string.h>
#include <stdio.h>


  int checkPalindrome(char string[MAX]);
  int checkRecPalindrome(char string[MAX]);


  int main(void){
    char checkString[MAX], chr[5] = {"exit"};
    do{
      printf("input string to check if it is a palindrome, or input exit to end\n");
      fflush(stdout);
      gets(checkString);
      if(strcmp(checkString, chr) != 0){
        /*call copies and reverses string to copy and sends back result of strcmp*/
        if(checkPalindrome(checkString) == 1)
          printf("The word is a palindrome(iterative)\n");
        else
          printf("The word is not a palindrome(iterative)\n");
        if (checkRecPalindrome(checkString))
          printf("The word is a palindrome (recursive)\n");
        else
          printf("The word is not a palindrome(recursive)\n");
      }
      else
        printf("Quitting...");
       /*loop is continued until checkString matches chr with strcmp*/
    }while(strcmp(checkString, chr) != 0);
    return 0;
  }
  int checkPalindrome(char string[MAX]){             /*strrev could also be used for a shorter code*/
    char revString[MAX];
    int a, b = (strlen(string) - 1) ;
    for(a = 0; a < strlen(string); ++a){
      revString[b] = string[a];
      --b;
    }
    revString[strlen(string)] = '\0';
    if(strcmp(string, revString) == 0)
      return 1;
    else
      return 0;
  }
  int checkRecPalindrome(char string[MAX]){
    static int a = 0;                               
    int strLgt = strlen(string) - a;                 
    if(strLgt > a){                                  
      if(string[a] == string[strLgt - 1]){
        a++;
        return checkRecPalindrome(string);
      }
      else
        return 0;
    }
    a = 0;
    return 1;
  }

There are situations where a function needs to keep a static state; this is not one of them. That value would normally be passed as one of the parameters to the function. (Actually you would probably pass the "length" of the string -- the original caller would pass the actual length, and then the recursive function calls would knock two off each time.)

I don't know exactly how that makes it seem "iterative" though.

the assignment said to create the recursive function with 1 parameter only.

You can do it with one parameter and the return value

actually he said that we could use a helper function I had no idea what he meant. I will take a look at Barney's functions. This forum is great for a beginner!