Find the nearest lesser and nearest greater number in an array

Posted on Apr 23, 2020

C program to find the nearest lesser and nearest greater number, to the number entered, from the array.

Program

#include<stdio.h>
#include<conio.h>
#define MAX 50

void main()
{
	int arr[MAX];
    int i, n, num, diff;
    int near_small, near_big, big_diff, small_diff;

    printf("Enter the number of elements in the array\t:");
    scanf("%d",&n);
    printf("Enter the elements\n");
    for(i=0;i<n;i++)
    {
        printf("Element %d\t:",i+1);
        scanf("%d",&arr[i]);
    }
    printf("\nEnter the number from which nearest lesser and nearest greater is to be found\t:");
    scanf("%d",&num);

    near_big = 0;
    near_small = 0;
    diff = 0;
    for(i=0;i<n;i++)
    {
        if(arr[i] > num)
        {
            diff = arr[i] - num;
            if(diff < big_diff)
            {
                near_big = arr[i];
                big_diff = diff;
            }

        }
        else if(arr[i] < num)
        {
            diff = num - arr[i];
            if(diff < small_diff)
            {
                near_small = arr[i];
                small_diff = diff;
            }
        }
    }

    if(near_big == 0)
    {
        printf("\nNearest lesser number\t:%d",near_small);
        printf("\nNearest greater number does not exist");
    }
    else if(near_small == 0)
    {
        printf("\nNearest lesser number does not exist");
        printf("\nNearest greater number\t:%d",near_big);
    }
    else
    {
        printf("\nNearest lesser number\t:%d",near_small);
        printf("\nNearest greater number\t:%d",near_big);
    }

    getch();
}

Output

********** Run1 ********** 

Enter the number of elements in the array       :4
Enter the elements
Element 1       :45
Element 2       :12
Element 3       :56
Element 4       :23

Enter the number from which nearest lesser and nearest greater is to be found   :30

Nearest lesser number   :23
Nearest greater number  :45


********** Run2 ********** 

Enter the number of elements in the array       :4
Enter the elements
Element 1       :45
Element 2       :52
Element 3       :56
Element 4       :23

Enter the number from which nearest lesser and nearest greater is to be found   :23

Nearest lesser number does not exist
Nearest greater number  :45


********** Run3 ********** 

Enter the number of elements in the array       :4
Enter the elements
Element 1       :41
Element 2       :52
Element 3       :12
Element 4       :56

Enter the number from which nearest lesser and nearest greater is to be found   :56

Nearest lesser number   :52
Nearest greater number does not exist