Program To Calculate The Factorial Of Number Entered By the User

Program:

#include <iostream>  
using namespace std;  
int main() {  
  int n, fact = 1;  
  cout << "Enter a positive integer: ";  
  cin >> n;  
  if(n < 0) {  
    cout << "Error: Please enter a positive integer" << endl;  
    return 1;  
  }  
  for(int i = 1; i <= n; ++i) {  
    fact *= i;  
  }  
  cout << "Factorial of " << n << " is " << fact << endl;  
  return 0;  
}  

Output:

Working Of The Program:

Here is how this program works:

1. The code prompts the user to enter a positive integer and reads it from the standard input using the cin statement.

2. An integer variable fact is initialized with a value of 1, which will store the entered number's factorial.

3. The code checks whether the entered number is less than zero. If it is, an error message is printed to the console and the program terminates with a return code of 1. This is done to ensure that the entered number is positive, as the factorial is defined only for positive integers.

4. A for loop is used to compute the factorial of the entered number. The loop variable i is initialized to 1 and iterates until i is greater than the entered number n.

5. In each iteration of the loop, the current value of fact is multiplied by the value of i, and the result is stored back in fact. This updates the value of fact to be the product of all the integers from 1 to n.

6. After the loop completes, the final value of fact contains the factorial of the entered number, which is printed to the console using the cout statement.

7. The program terminates with a return code of 0, indicating successful execution.