Write a C++ program to read from the user an integer number of 4 digits and display it in reverse order. For example, if the input is 5723 the output should be 3275. (Hint use / and %). The program should display “Invalid input” if the input value is not a 4 digits number.

#include <iostream>

using namespace std;

int main() {

 int n, reversedNumber = 0, remainder;

 cout << "Enter a number: ";

 cin >> n;

 int length = to_string(n).length();

 if (length == 4){

   while(n != 0) {

     remainder = n%10;

     reversedNumber = reversedNumber*10 + remainder;

     n /= 10;

   }

   cout << "Reversed Number = " << reversedNumber << endl;

 }

 else{

   cout << "Invalid Input!" << endl;

 }

 return 0;

}

Explanation:

So, it's pretty easy. It finds the remainder to reverse the number and for the invalid input part, you convert the input into a string and then use .length() to find the length. Then you can reverse the number and show whatever output

that without the operating systems you would have to control and synchronize computer hardware.