Thread: Recursive binary search program help.

Im attempting to write a binary search function which calls itself recursively. I cant get it to call itself recursively w/ out freezing. The code is below, it freezes right after "calling function recursively"

I tried setting found =1 right before it calls itself, but that doesn't work meaning the program doesnt get stuck in an infinite loop, it just freezes when it calls itself.

I think it might have to do w/ allocating and freeing the memory, but am really not sure.

Thanks for the help!

Code:

#include <stdio.h>

	
int
BinarySearch(int *asize, int numbers[*asize], int *snum, int *searcher, int *iter, int *top, int *bottom, int *middle, int *found)
{

	*middle = (int)(((*top + *bottom)/2.0)+.5);	
	printf("top = %d middle = %d bottom = %d\nsearcher = %d snum = %d &numbers[*middle] = %d found = %d", *top, *middle, *bottom, *searcher, *snum, numbers[*middle], *found);

	if(*bottom < *top && *found == 0) {
		if(searcher == numbers[*middle]) {
			*found = 1;
			*iter++;
			printf("found %d", &numbers[*middle]);
		}
		else if(numbers[*middle] > *searcher) {
             *top = *middle - 1;
             printf("top = %d middle = %d bottom = %d\nsearcher = %d snum = %d &numbers[*middle] = %d", *top, *middle, *bottom, *searcher, *snum, numbers[*middle]);
            printf("calling function recursively");
            return (BinarySearch(*asize, numbers, *snum, *searcher, *iter, *top, *bottom, *middle, *found));
        }
        else {
             *bottom = *middle + 1;  
             printf("top = %d middle = %d bottom = %d\nsearcher = %d snum = %d &numbers[*middle] = %d", *top, *middle, *bottom, *searcher, *snum, numbers[*middle]);
             return (BinarySearch(*asize, numbers, *snum, *searcher, *iter, *top, *bottom, *middle, *found));
        }     
      
    }
    else{}
    
    if(*found == 1) {
         return(0);
         }
    else {
         printf("top = %d middle = %d bottom = %d\nsearcher = %d snum = %d &numbers[*middle] = %d", *top, *middle, *bottom, *searcher, *snum, numbers[*middle]);
        

    }
}

Originally Posted by Todd Burch

When you call BinarySearch recursively here:

Code:

return (BinarySearch(*asize, numbers, *snum, *searcher, *iter, *top, *bottom, *middle, *found));

You are using the indirection operator on most all of the variables. As an example, asize is a pointer, and you are telling the compiler to pass what asize points to, which is an int, as opposed to just passing the pointer.

Lose the indirection operator and try it.

Todd

THANKS!