Question

How to reverse input number into an array in C

Answer 1

#include <stdio.h> 
#include <math.h>
 
int countdigits(int n);
 
int main(void)
{   
     int arr[6] = {0}, n, e;
 
     printf("Enter a number:  ");
     scanf("%d",&n);
      
     int size = countdigits(n);
      
     for (int i = size - 1; i >= 0; i--)
     {
          e = pow(10, i);
          arr[i] = n/e;
          n = n%e;
     }
     for (int i = 0;i < size; i++)
         printf("%d", arr[i]);
          
     return 0;
}
 
int countdigits(int n)
{
    int count = 0;
 
    while (n != 0)
    {
        n /= 10;
        count++;
    }
     
    return count;
}
 
  
/*
run:
    
Enter a number:  12345
54321
 
*/

 

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Answer 2

#include <stdio.h> 

int countdigits(int n);

int main(void)
{   
    int arr[10] = {0}, n;
 
    printf("Enter a number:  ");
    scanf("%d",&n);
      
    int size = countdigits(n);
      
    int i = 0;
    while (n != 0)
    {
          arr[i++] = n%10;
          n = n/10;
    }
    for (int i = 0; i < size; i++)
         printf("%d", arr[i]);
         
    return 0;
}

int countdigits(int n)
{
    int count = 0;
 
    while (n != 0)
    {
        n /= 10;
        count++;
    }
     
    return count;
}

 
/*
run:
   
Enter a number:  12345
54321

*/

 

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