Binary Search: Search an element in sorted array recursively

C program for binary searching: Binary searching recursively program. Here is simple C program for binary searching using recursion.
Binary searching prerequisite's that array should be sorted. In unsorted array binary searching does not works.

C Program:

#include<stdio.h>
 
int BSearch(int arr[],int low,int high,int num)
{
 /*Function will return -1 if number is not
 present in array 
 For example if array is 1,2,3 and we are searching 
 for 4 then in first call mid= 2/2 =1 and number is 
 greater then arr[mid] = 2 then low will become 
 mid+1 = 2 now high = low
 in next call mid = 2+2/2 = 2 so number is 
 greater then arr[mid] = 3 now low will become 
 become mid+1 = 3  and high<low(2<3) so to terminate function 
 we use this if loop */
 
 if(high<low)
 return -1;
 /* For large high we use low+(high-low)/2
 because of overflow */
 /* If high is max value of integer and low is 
 half of high then if we add low+high it will  
 be overflow */
 int mid=(low+high)/2;
 
 if(arr[mid]==num)
 return mid;
 else
 if(arr[mid]<num)
  return BSearch(arr,mid+1,high,num);
 else
 return BSearch(arr,low,mid-1,num);
}
 
int main()
{
 int arr[]={1,2,3,4,5,6,7,12,13,14};
 
 int size = sizeof(arr)/sizeof(arr[0]);
 
 int num;
 
 printf("Enter a number: ");
 scanf("%d",&num);
 
 int index = BSearch(arr,0,size-1,num);
 
 if(index==-1)
 printf("Number is not in array\n");
 else
 printf("number is at index %d ",index);
 
 return 0;
}

Related: Binary Searching iterative method