Arrange all even numbers at top and all odd numbers at bottom of an array

Posted on Apr 24, 2020

C program to arrange all even numbers at top and all odd numbers at bottom of an array.

Program

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

void read_array(int a[MAX], int n)
{
    int i;
    for(i=0;i<n;i++)
    {
        printf("Element %d\t:",i+1);
        scanf("%d",&a[i]);
    }
}

void print_array(int a[MAX], int n)
{
    int i;
    for(i=0;i<n;i++)
    {
        printf("Element %d\t:%d\n",i+1,a[i]);
    }
}

void segregate_evenodd(int arr[MAX], int n)
{
    int left, right, temp;

    left = 0;
    right = n-1;

    while(left < right)
    {
        while(arr[left]%2 == 0 && left<right)
        {
            left++;
        }
        while(arr[right]%2 == 1 && left<right)
        {
            right--;
        }
        if(left < right)
        {
            temp = arr[left];
            arr[left] = arr[right];
            arr[right] = temp;

            left++;
            right--;
        }
    }
}

void main()
{
    int arr[MAX];
    int n;

    printf("Enter the number of elements in the array\t:");
    scanf("%d",&n);

    printf("Enter the elements of the array\n");
    read_array(arr, n);

    segregate_evenodd(arr, n);

    printf("\nModified array is\n");
    print_array(arr, n);

    getch();
}

Output

Enter the number of elements in the array       :9
Enter the elements of the array
Element 1       :12
Element 2       :23
Element 3       :34
Element 4       :45
Element 5       :56
Element 6       :67
Element 7       :78
Element 8       :89
Element 9       :90

Modified array is
Element 1       :12
Element 2       :90
Element 3       :34
Element 4       :78
Element 5       :56
Element 6       :67
Element 7       :45
Element 8       :89
Element 9       :23