C program to Convert Number to Words

#include <stdio.h>

int main()

{
    int num,rem=0,sum=0;

    printf("enter the number :");

    scanf("%d",&num);

    while(num!=0)

    {

        rem=num%10;

        sum=sum*10+rem;

        num=num/10;

    }

    while(sum!=0)

    {

        rem=sum%10;

        switch(rem)

        {

        case 0:
            printf("Zero ");

            break;

        case 1:
            printf("One ");

            break;

        case 2:
            printf("Two ");

            break;

        case 3:
            printf("Three ");

            break;

        case 4:
            printf("Four ");

            break;

        case 5:
            printf("Five ");

            break;

        case 6:
            printf("Six ");

            break;

        case 7:
            printf("Seven ");

            break;

        case 8:
            printf("Eight ");

            break;

        case 9:
            printf("Nine ");

            break;

        default:
            printf("please enter valid number ");
            exit(0);

        }

        sum=sum/10;

    }

    return 0;

}