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Sunday, February 16, 2014

Convert a Number into Reverse Number Program in C Plus Plus

C++ Reverse Number Conversion Program Logic



Q: Write a C++ Program to input an integer number and display its Reverse Number. For example if the input is the number 123, the Reverse Number will be 321.

convert-reverse-number-program-c-plus-plus
  • First of all we suppose that the number entered is 123.
  •  Let the given number num = 123
  • Copy the number in temporary variable temp so that temp = 123

First Iteration of While Loop

  • We start a while loop with condition temp>0. Since temp=123 so loop will start for first time.
  • Now we will divide number 123 by 10 so that the remainder R = 3 and Quotient Q = 12
  • Put the values in statement rev = rev * 10 + R
  • rev = 0 * 10 + 3
  • rev = 3
  • Assign the value of Quotient Q to temp so that temp = 12 now.
  • Since temp 12 is >0, so the while loop will execute again.
  •  

Second Iteration of While Loop

  • Now we will divide number temp 12 by 10 so that the remainder R = 2 and Quotient Q = 1
  • Put the values in statement rev = rev * 10 + R
  • rev = 3 * 10 + 2
  • rev = 30+2
  • rev = 32
  • Assign the value of Quotient Q to temp so that temp = 1 now.
  • Since temp 1 is >0, so the while loop will execute again.

 Third Iteration of While Loop

  •  Now we will divide number temp 1 by 10 so that the remainder R = 1 and Quotient Q = 0
  • Put the values in statement rev = rev * 10 + R
  • rev = 32 * 10 + 1
  • rev = 320+1
  • rev = 321
  • Assign the value of Quotient Q to temp so that temp = 0 now.
  • Since temp 0 is not >0, so the condition temp>0 will evaluate to false so that the while loop will terminate.
reverse-number-program-code-in-c-plus-plus

Conclusion

       So the Required Reverse Number is 321.

The Actual C++ Code of Reverse Number Program


/*
Program to input a number, then display its Reverse number.
(c) Www.EasyCppProgramming.Blogspot.Com
*/


#include<iostream.h>
#include<conio.h>
#include<math.h>
void main()
{
     int num, temp, rev=0, R, Q;

     clrscr();

     cout<<"Enter a number to reverse=";

     cin>>num;

     temp = num;

     while ( temp>0 )

     {

       Q = temp/10;
       R = temp % 10;
       rev = rev*10 + R;

       temp = Q;

     }

     cout<<"\n The Reverse Number = "<<rev;
     getch();

     }