Introduction

In this program, you will learn to reverse the digits of the integer value entered by the user in the C++ language.

For example, if the number is 98542, then this code will reverse the number, and the output will be 24589.

To understand the program, learn the following basic concepts of C++ programming

1. Operators

2. while and do-while loop

Program

#include<iostream>
using namespace std;
int main()
{
int n;
cout<<"Enter an integer: ";
cin>>n;


int rem=0; // rem is used for the remainder
int z=0;
while(n>0)
{
rem=n%10; // fetching the last digit
z=z*10+rem; // formation of reversed integer
n=n/10; // elimination of the last digit
}
cout<<"Reversed number is: "<<z;
return 0;
}

Output

Explanation

‘n’ will store the integer entered by the user.

int rem=0;

‘rem’ variable is initialized with a 0 value to find the remainder.

int z=0; ‘z’ variable is initialized with a 0 value to hold the reversed integer.

The value of ‘n’ is 9850023

while(n>0)

the above condition is true

rem=n%10; this will return rem=9850023%10=3

z=z*10+rem;

Since z is 0, therefore, from the above statement, z=0*10+3=3

n=n/10; the value of ‘n’ is updated to 9850023/10=985002, thus vanishes the last digit.

Again, the condition in the while loop will become true, and the same procedure will take place for n=985002

rem=985002%10=2

z=3*10+2=32

n=985002/10=98500

Again, the condition in the while loop will become true, and the same procedure will take place for n=98500

rem=98500%10=0

z=32*10+0=320

n=98500/10=9850

Again, the condition in the while loop will become true, and the same procedure will take place for n=9850

rem=9850%10=0

z=320*10+0=3200

n=9850/10=985

Again, the condition in the while loop will become true, and the same procedure will take place for n=985

rem=985%10=5

z=3200*10+5=32005

n=985/10=98

Again, the condition in the while loop will become true, and the same procedure will take place for n=98

rem=98%10=8

z=32005*10+8=320058

n=98/10=9

Again, the condition in the while loop will become true, and the same procedure will take place for n=9

rem=9%10=9

z=320058*10+9=3200589

n=9/10=0

Now the condition in the while loop becomes false, and the loop terminates.

Thus, the final value of ‘z’ is 3200589.