Binary search implementation in C

              Searching is a process of finding an element from a group of elements. Binary search is one of the efficient search algorithms. Let us implement it in C language.

Implementation:

• This algorithm follows a method as follows.
• First, find the middle element.
• Check the element to be searched with middle element.
• If it is small, search the element in the left child of the array.
• If it is large, go for right side.
• Repeat this process to find the exact position.

C Code:

#include <stdio.h>

int binarySearch(int a[], int n, int key) {

    int low = 0, high = n - 1;

    while (low <= high) {

        int mid = (low + high) / 2;

        if (a[mid] == key)

            return mid;  // yes ,it is Found

        else if (a[mid] < key)

            low = mid + 1;  // Search in right half

        else

            high = mid - 1; // Search in left half

    }

    return -1; // It is Not found

}

int main() {

    int a[10];

    int n,key,i;

    printf("Enter the number of elements:");

    scanf("%d",&n);

    printf("Enter the elements");

    for(i=0;i<n;i++)

    {

        scanf("%d",&a[i]);

    }

    printf("Enter the key value to search using Binary Search");

    scanf("%d",&key);

    int s = binarySearch(a, n, key);

    if (s != -1)

        printf("Element is found at index %d\n",s);

    else

        printf("Sorry, the element is not found\n");

    return 0;

}

Output1: Element is found

Compile and run the program to get the output.

Enter the number of elements:5

Enter the elements34 45 56 67 78

Enter the key value to search using Binary Search 45

Element is found at index 1

Output2: Element is not found

Enter the number of elements:6

Enter the elements45 56 67 78 89 91

Enter the key value to search using Binary Search 23

Sorry, the element is not found

Yes. That’s all. two different outputs are shown here to clear explanation. Hope, you found useful in this coding. Keep coding!!!