我在编写阶乘程序时遇到困难

Question

程序应该要求用户输入一个正整数并打印一个阶乘 table。如果输入小于 0，输出或程序应该停止。

给我一个正整数：5

输出：

5个！ = 5 x 4 x 3 x 2 x 1

5的阶乘是120

给我一个正整数：-5

输出：输入无效！程序停止

P.s: 我是初学者。我正在使用 Netbean IDE

Answer 1

您可以检查数字是否小于 0，否则计算阶乘

let x = prompt('Please enter a positive integer');

if (x < 0) {
  console.log('invalid Input! Programmed Stop')
} else {
  let val = 1;
  for (let k = 1; k <= x; k++) {
    val *= k
  }
  console.log(val)
}

Answer 2

这应该有效。只需遍历数字即可。

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（假设输入在变量input中）：

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.")}

我在编写阶乘程序时遇到困难

I am having difficulties writing a factorial program

java

factorial