Question

How to implement binary search using recursion in C

Answer 1

#include <stdio.h>

#define LEN 10

int binary_search(int arr[], int n, int start, int end);

int main(void)
{
	int idx, start, end;
	int arr[LEN] = { 2, 5, 7, 8, 9, 12, 45, 78, 98, 100 };

	start = 0;
	end = LEN - 1;

	idx = binary_search(arr, 45, start, end);

	if (idx != -1) 
		printf("Found: arr[%d] = %d", idx, arr[idx]);
    else
		printf("Not Found");

    return 0;
}
int binary_search(int arr[], int n, int start, int end) 
{
   int mid;
 
   if (start > end)
       return -1;
 
   mid = (start + end) / 2;
 
   if (n == arr[mid]) 
       return (mid);
   else if (n < arr[mid]) 
			binary_search(arr, n, start, mid - 1);
		else 
			binary_search(arr, n, mid + 1, end);
}
  
    
/*
      
run:

Found: arr[6] = 45

*/

 

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