# Reverse of a Number using do-while loop in C

## Program code to find Reverse of a Number in C:

```#include<stdio.h>
#include<conio.h>
void main()
{
int n,a,r,s=0;
clrscr();

printf("\n  Enter The Number:");
scanf("%d",&n);
a=n;

//LOOP FOR FINDING THE REVERSE OF A NUMBER
do
{
r=n%10;
s=s*10+r;
n=n/10;
}while(n>0);

printf("\n  The Reverse Number of %d is %d",a,s);
getch();
}
```

## Working:

• First the computer reads a number from the user.
• Then using do-while loop the reverse number is calculated and stored in the variable ‘s’.
• Finally the reverse of a given number is printed.

## Step by step working of the above C program:

Let us assume a number entered is 1234.

So n=1234 , s=0

1. r=n%10       (r=1234%10)      So  r=4

s=s*10+r     (s=0*10+4)         So  s=4

n=n/10        (n=1234/10)       So  n=123

1. n>0  (123>0)  do-while loop condition is true

r=n%10       (r=123%10)      So  r=3

s=s*10+r    (s=4*10+3)        So  s=43

n=n/10       (n=123/10)       So  n=12

1. n>0  (12>0)  do-while loop condition is true

r=n%10       (r=12%10)         So  r=2

s=s*10+r    (s=43*10+2)      So  s=432

n=n/10       (n=12/10)          So  n=1

1. n>0  (1>0)  do-while loop condition is true

r=n%10       (r=1%10)             So  r=1

s=s*10+r    (s=432*10+1)      So  s=4321

n=n/10       (n=1/10)              So  n=0

1.  n>0  (0>0)  do-while loop condition is false

It comes out of the do-while loop and prints the reverse number which is stored in variable “s”.

1. Thus the program execution is completed.

## Output:  