C Exercises: Find the position of a target value within a sorted array using Binary search

Last update on November 01 2025 11:50:49 (UTC/GMT +8 hours)

1. Binary Search Variants

Write a C program to find the position of a target value within a sorted array using binary search.
Note: Binary Search : In computer science, a binary search or half-interval search algorithm finds the position of a target value within a sorted array. The binary search algorithm can be classified as a dichotomies divide-and-conquer search algorithm and executes in logarithmic time.
Given a sorted array arra[] of n elements, write a function to search a given element x in arra[].

Visual presentation - Binary search algorithm :

Sample Solution :

C Code :

#include<stdio.h>
void main()
{
    // Variable declarations
    int arra[100], i, n, x, f, l, m, flag = 0;
    // Prompting user for input
    printf("Input no. of elements in an array\n");
    // Getting user input for the number of elements in the array
    scanf("%d", &n);
    // Prompting user for input
    printf("Input %d value in ascending order\n", n);
    // Getting user input for the elements of the array
    for(i = 0; i < n; i++)
        scanf("%d", &arra[i]);
    // Prompting user for input
    printf("Input the value to be search : ");

    // Getting user input for the value to be searched
    scanf("%d", &x);
    // Binary Search logic
    f = 0;
    l = n - 1;
    while (f <= l)
    {
        m = (f + l) / 2;
        if (x == arra[m])
        {
            flag = 1;
            break;
        }
        else if (x < arra[m])
            l = m - 1;
        else
            f = m + 1;
    }
    // Checking if the value was found or not and printing the result
    if (flag == 0)
        printf("%d value not found\n", x);
    else
        printf("%d value found at %d position\n", x, m);
}

Sample Output:

Input  no. of elements in an array                                                                            
3                                                                                                             
Input  3 value in ascending order                                                                             
15                                                                                                            
18                                                                                                            
20                                                                                                            
Input  the value to be search : 15                                                                            
15 value  found at 0 position

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to implement binary search recursively on a sorted array of integers.
Write a C program to find the first occurrence of a target value in a sorted array with duplicate entries using binary search.
Write a C program to perform binary search on a sorted array of strings using a custom comparator function.
Write a C program to count the number of comparisons made during a binary search on a sorted array.

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