CPP program to print factorial of a number

The below program prints factorial of a number using a loop and using recursion. The CPP cout object is used to output the result on the screen. The factorial of a number can be calculated for positive integers only and is represented by n!.

n! = n*(n-1)*(n-2)*……*1

0! = 1

Code: Using Loop

```#include <iostream.h> using namespace std;   int main() { int num,i; int f = 1;   cout << "Enter a number:"; cin >> num;   for (i=num; i>1; i--) f = f * i;   cout << num << "!" << "=" << f; return 0; }```

Output

```Enter a number:10 10!=3628800```

Code: Using Recursion

```#include <iostream.h> using namespace std;   int main() { int x; cout << "Enter a Number: "; cin >> x; int factorial(int); int fact=factorial(x); cout<<"Factorial of " << x << " is: "<<fact<<endl; return 0; }   int factorial(int n) { if(n<0) return(-1); if(n==0) return(1); else { return(n*factorial(n-1)); } }```

Output

```Enter a Number: 10 Factorial of 10 is: 3628800```
Posted in CPP