在 Javascript 中使用 while 循环对数字进行阶乘

Question

I need help creating the code to find the factorial of a number. The task is to

1. Create a variable to store your answer and initialize it to one
2. Create a loop that beings at the given value, fact
3. Check if fact is one or zero
4. multiply fact with your answer variable
5. At the end of the loop decrease fact
6. Print answer using console.log

The pseudocode is

while(factorial)
  if factorial == 0 or factorial == 1
    break 
  result => result * factorial
  factorial  => factorial - 1

My code below isn't complete because I'm confused by the pseudocode.

function nth_fact(nth){
var a = 1
while(nth_fact)
if (nth_fact == 0 || nth_fact == 1){
    break;
result => result * nth_fact
nth_fact => nth - 1
console.log() 
}
}

Answer 1

At first lets examine what went wrong:

var a = 1

What is a ? Its definetly not a good name for a variable. Maybe name it to result ? The same applies to nth which should be named factorial and nth_fact which should rather be factorize or sth. You should also always use ; to end a statement.

while(nth_fact)

As your while loop contains multiple statements (the if and the two assignments) you need to open a block here by using { right after the condition. nth_fact refers to the function, you rather want to take factorial here.

 if (nth_fact == 0 || nth_fact == 1){
   break;

Now you open a block statement for the if, but you never close it. So you need another } after the break.

result => result * nth_fact
nth_fact => nth - 1
console.log() 

=> is the arrow function expression, but you want the assignment operator = . Also you need to pass something to console.log, eg console.log(result)

All together:

 function factorize(factorial){
   var result = 1;
  while(factorial){
     if (factorial == 0 || factorial == 1){
        break;
     }
     // ?
     factorial = factorial - 1;
     console.log(result);
  }
  return result;
}

Answer 2

That pseudocode is indeed confusing, because what it calls factorial is actually not the factorial -- it's the current value, which the result (which is actually the factorial we're looking for) is multiplied by. Also, if is superfluous, because while already checks for the same condition. So the correct pseudocode would be

currentValue = argument
factorial = 1

while (currentValue > 1)
    factorial = factorial * currentValue
    currentValue = currentValue - 1

// now, 'factorial' is the factorial of the 'argument'

Once you get this sorted out, here's a bonus assignment:

• create a function range(a, b) that creates an array of numbers from a to b . For example, range(5, 8) => [5, 6, 7, 8]
• create a function product(array) that multiples array elements by each other. For example, product([2, 3, 7]) => 42
• write the factorial function using product and range

Answer 3

 function factorial(num) { var result = 1 while (num) { if ((num) == 0 || (num) == 1) { break; } else { result = result * num; num = num - 1; } } return `The factorial of ${val} is ${result}` } let val = prompt("Please Enter the number : ", "0"); var x = parseInt(val); console.log(factorial(x));

Answer 4

A Short And Clean Code is :

 let number = 5; let numberFactorial = number; while(number > 1){ numberFactorial = numberFactorial * (number-1); number--; } console.log(numberFactorial);

Answer 5

I solve this this way

 function factorial(number) { let num = 1; let result = 1; while (num <= number) { result = result * num; num++; } return result; } const myNumber = factorial(6); console.log(myNumber);

Answer 6

You used the right approach. Just the syntax was wrong. Here it is:

function nth_fact(nth){
var result = 1 ;
while(nth){
  if ((nth) == 0 || (nth) == 1)
    break ;
  result = result * nth;
  nth = nth - 1
 }
console.log(result); 
return result;
}