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();
}

Related: Reverse of a Number using while loop in C

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:

reverse of a number

reverse of a number

TO DOWNLOAD THE PROGRAM CODE : CLICK HERE

 

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