factorial in different ways in CPP

factorial.cpp

#include <iostream>
using namespace std;

int recursive_fact(int n){

  /*
  ex: fact(n) = 1*2*3........*(n-1)*n
      so, (fact(n-1)*n) Gives us the answer
  */

  if(n==0){return 1;}else{
    return recursive_fact(n-1)*n;
  }

}

int using_for(int n){
  int fact = 1;
  if(n==0){return 1;}else{
    for(int i=1;i<=n;i++){
      fact *= i;
    }
    return fact;
  }
}

int using_while(int n){
  if(n==0){return 1;}else{
  int fact=1,i=1;
  while(i <= n){
    fact *= i;
    i++;
  }
  return fact;
 }
}

int main(){
  int n = 3;
  cout << recursive_fact(n) << endl;
  cout << using_for(n) << endl;
  cout << using_while(n) << endl;
  return 0;
}