Binary Search

Write a program in C to search an element in an array using binary search.

To search for an element in an array using Binary Search the array should be sorted.

Code:

#include <stdio.h>

int main()
{
    int i,first,last,middle,n,element,array[100];
   
    // read number of elements
    printf("Enter number of elements to enter in the array (max 100):");
    scanf("%d",&n);
   
    // input elements in the array
    printf("Enter %d elements one by one in ascending order:\n",n);
    for(i=0;i<n;i++)
        scanf("%d",&array[i]);
   
    // read element to search for
    printf("Enter the element to be searched in the array:");
    scanf("%d",&element);
   
    // algorithm for binary search
    first = 0;
    last = n-1;
    middle = (first+last)/2;
   
    while(first<=last){
        if(element > array[middle])
            first = middle+1;
        else if(element < array[middle])
            last = middle-1;
        else{
            printf("%d found at position %d",element,middle+1);
            break;
        }
        middle = (first+last)/2;
    }
    if(first>last)
        printf("%d not found in the array!",element);

    return 0;
}