How to print a number in spellings?

Question

So Here I am trying to write a code, that converts a numerical number to its spelling format. For example, the user inputs any number like 320, then the output should be "Three Two Zero". Following is what I Have tried-

#include <stdio.h>
void main(){
long int num,rev=0 ;
printf("Enter any number to print in words: ");
scanf("%ld",&num);
while(num!=0){
    rev=(rev*10)+(num%10);
    num/=10 ;
}
while(rev!=0){
    long int x=rev%10;
    switch(x){
        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;
       }
   }
 }

Now the problem is that, this code is producing an infinite loop, like I input a number say 21, then it starts printing "Two Two Two Two........." till infinity.

Please Help me in resolving this question.

Answer 1

You need something that will make "rev!=0" true, which is rev = rev / 10 after the end of the switch. But creating an array and assigning zero, one, two, etc. and calling them using index could be better, I think you can think about this.

#include <stdio.h>
void main(){
long int num,rev=0 ;
printf("Enter any number to print in words: ");
scanf("%ld",&num);
while(num!=0){
    rev=(rev*10)+(num%10);
    num/=10 ;
}
while(rev!=0){
    long int x=rev%10;
    switch(x){
        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;
       }
       rev = rev / 10;
   }
 }

And this is array approach:

#include <stdio.h>
void main(){
long int num,rev=0 ;
printf("Enter any number to print in words: ");

num = 123456789;

const char arr[10][6]= {
    "Zero", "One", "two", "three", "four", "five", "six", "seven", "eight", "nine"
    };

while(num!=0){
    rev=(rev*10)+(num%10);
    num/=10 ;
}
while(rev!=0){
    long int x=rev%10;
    printf("%s ", arr[x]);
    rev = rev / 10;
   }
}