khuang8493
7/5/2018 - 4:22 AM

Iterative binary search function example

A iterative binary search function. It returns location of x in given array arr[l..r] if present, otherwise -1. This uses a loop to check each element. Recursive method is better. It's a better way to solve problems that might be too complex if using loop or other methods.

iterative_binary_search.c
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// C program to implement iterative Binary Search
#include <stdio.h>
 
// A iterative binary search function. It returns
// location of x in given array arr[l..r] if present,
// otherwise -1

int binarySearch(int arr[], int l, int r, int x)
{
    while (l <= r)
    {
        int m = l + (r-l)/2;
 
        // Check if x is present at mid
        if (arr[m] == x)
            return m;
 
        // If x greater, ignore left half
        if (arr[m] < x)
            l = m + 1;
 
        // If x is smaller, ignore right half
        else
            r = m - 1;
    }
 
    // if we reach here, then element was
    // not present
    return -1;
}
 
int main(void)
{
    int arr[] = {2, 3, 4, 10, 40};
    int n = sizeof(arr)/ sizeof(arr[0]);
    int x = 10;
    int result = binarySearch(arr, 0, n-1, x);
    (result == -1)? printf("Element is not present"
                                       " in array")
               : printf("Element is present at "
                                "index %d", result);
    return 0;
}