Reverse number in cpp

Reverse number in cpp is another easy and simple program which mostly asked in exams.

In this tutorial, we are going to learn how to reverse a number programmatically

Reverse Number Logic

We separate digits in number by modulus operation which gives us a digit in a number.

Rem = number % 10

After separating number we store that digit in another variable with considering its unit places which we perform as

Reverse = Reverse × 10 + Remember

We repeated step 1 and 2 till number ends.

Reverse Number Example

Number = 342

Reverse number = 243

C++ Program to Reverse a Number

12345678910111213141516171819202122232425262728#include <iostream>using namespace std;int main(){ int temporary ,n,rev=0,x;cout<<“Enter a number\n”;cin>>n;temporary =n;while(n>0){ x=n%10;rev=rev*10+x; n=n/10; }cout<<“The reverse of “<<temporary<<“is “<<rev;    return 0;}

Output :

reverse number in cpp
reverse number in cpp

Explanation :-

1. Here we did initialization for

temporary ->To store the entered value(i.e ‘n’) as you will come to know at the end of the program

n->To store number given by a user.

rev->To store the reverse of a number.It is initialized to zero

x->To store n%10.

2. First of all, we got a number ‘n’ from a user and then stored it in a temporary variable called as ‘temporary ‘ for restoring the value.(remember this point).

3. Now the main logic comes here

let the number ‘n’ be 321 and as 321>0, while loop gets executed

then x=321%10—>which is 1.



The rev for the first loop execution is rev=1.

4. Now the number ‘n’ has become ’32’ and n>0, while loop executes for the 2nd time.

then x=32%10—>which is 2.



The rev when loop executed the second time is rev=12.

5. Now the number ‘n’ has become ‘3’ and n>0, while loop executes for the 3rd time

then x=3%10—>which is 3.



The rev when loop executed the third time is rev=123.

6. Now as the number of variable ‘n’ is 0 which is not n>0 then the loop terminates.Then the final reverse is ‘123’.

7. So now I hope you understood why the temporary variable is used.It is because the value in ‘n’ becomes 0 at the end of the program so for restoring this value to print at the end we used ‘temporary ‘(as from the 2nd point).

8. Finally, it prints the value in ‘rev’.