Niuke.com's Programming Beginner Training Question 19: Reverse output a four-digit number

Using a loop to put the remainders into an array in turn Divide the number by 10

#include<stdio.h>
int main()
{
    
    
    int a;
    scanf("%d",&a);
    int a1[4];
    int i=0;
    while(a!=0)
    {
    
    
        a1[i]=a%10;
        i++;
        a=a/10;
    }
    for(i=0;i<4;i++)
    {
    
    
        printf("%d",a1[i]);
    }
    return 0;
}