Binary Search in C

binary_search.c

#include<stdio.h>
#define max_size 1000 //Maximum size ot the Array


int main(){
	int arr[max_size];
	int arr_size,i;
	int key;
	int lowerbound;
	int upperbound;
	int midPoint;
	int result = -1;
	printf("Enter the Size of the Array ");
	scanf("%d",&arr_size);
	
	//Get input
	printf("Enter %d elements in the array: ",arr_size);
	for(i=0; i<arr_size; i++){
		printf("Enter %d element",i);
		scanf("%d",&arr[i]);
	}
	
	//Prints all elements
	
	printf("\n Entered Elements in the array are : ");
	for (i=0;i<arr_size;i++)
	 {
	 	printf("%d, ", arr[i]);
	 }	
	 
	 //Get the element which needs to be searched
	 
	 printf("\n Enter the value to be searched ");
	 scanf("%d",&key);
	 
	 //Now search using binary search
	 //Remember binary search can be performed on sorted arrays only
	 //so if the array is unsorted, we need to use a sorting technique
	 //like merge sort to sort it first and then apply binary search	 
	 lowerbound = 0;
	 upperbound = arr_size-1;
	  
	 while(lowerbound <= upperbound ){
	    midPoint = (lowerbound + upperbound)/2;
	 	if(arr[midPoint] < key ){
	 		//if key is smaller than midpoint
	 		//key will be in upperhalf
	 		lowerbound = midPoint + 1;			  
		 }	
		 
		 else if(arr[midPoint] == key)  {
               //key found at midpoint
               result = midPoint+1;
			   printf("%d found at location %d . \n ",key,result);
		      break;
		 }
		 else{
		 	//if key is larger than midpoint
		 	//key will be in lower half
			   upperbound = midPoint - 1;
			 
		 }	
	
	 }
	 	 if(lowerbound > upperbound){
		 
		 printf("Key Not Found , Please Enter Valid Key !");
		 
		 }
	 

	
		 return 0;


}