I am having difficulties writing a factorial program

Question

the program should ask user for a positive integer and print a factorial table. And if the input is less than 0 the output or program should stop.

Give me a positive integer: 5

Output:

5! = 5 x 4 x 3 x 2 x 1

The factorial of 5 is 120

Give me a postive integer: -5

Output: invalid Input! Programmed Stop

P.s: i am a beginner. I am using Netbean IDE

Answer 1

This should work. Just loop through the numbers.

var input = prompt("What number would you like me to give you the factorial of?");
if (input > 0) {
  var answer = 1;
  var string = input + " =";
  for (var i = input; i >= 1; i--) {
    answer *= i;
    string += " " + i
    if (i != 1) {
      string += " x"
    }
  }

  console.log(string)
  console.log("The factorial of " + input + " is " + answer)
} else {console.log("Invalid input! Program stopped.")}

Java (assumes the input is in the variable input):

if (input > 0) {
  int answer = 1;
  String stringAnswer = input + " =";
  for (int i = input; i >= 1; i--) {
    answer *= i;
    stringAnswer += " " + i
    if (i != 1) {
      stringAnswer += " x"
    }
  }

  System.out.println(stringAnswer)
  System.out.println("The factorial of " + input + " is " + answer)
} else {System.out.println("Invalid input! Program stopped.")}