# Reverse of a Number using do-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
do
{
r=n%10;
s=s*10+r;
n=n/10;
}while(n>0);

cout<<"\n  The Reverse Number of "<<a<<" is "<<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 4321.

So n=4321 , s=0

1. r=n%10       (r=4321%10)      So  r=1

s=s*10+r     (s=0*10+1)         So  s=1

n=n/10        (n=4321/10)       So  n=432

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

r=n%10       (r=432%10)      So  r=2

s=s*10+r    (s=1*10+2)        So  s=12

n=n/10       (n=432/10)       So  n=43

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

r=n%10       (r=43%10)         So  r=3

s=s*10+r    (s=12*10+3)      So  s=123

n=n/10       (n=43/10)          So  n=4

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

r=n%10       (r=4%10)             So  r=4

s=s*10+r    (s=123*10+4)      So  s=1234

n=n/10       (n=4/10)              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:  ### 2 Responses

1. sohail Ahmad says:

out class wonder full

2. seid says:

thanks very much i love it