# Reverse of a Number using while loop in C++

## Program code to find Reverse of a Number:

```#include<iostream.h>
#include<conio.h>

void main()
{
int n,a,r,s=0;
clrscr();

cout<<"\n  Enter The Number:";
cin>>n;
a=n;

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

cout<<"\n  The Reverse Number of "<<a<<" is "<<s;
getch();
}
```

## Working:

• First the computer reads a number from the user.
• Then using 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 123.

So n=123 , s=0

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

r=n%10       (r=123%10)      So  r=3

s=s*10+r    (s=0*10+3)       So  s=3

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

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

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

s=s*10+r    (s=3*10+2)     So  s=32

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

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

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

s=s*10+r    (s=32*10+1)     So  s=321

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

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

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

1. Thus the program execution is completed.

## Output:  