here is an error i <= inputNumber
should be i < inputNumber
var inputNumber = prompt('Please enter an integer');
var total = 1;
for (i = 0; i < inputNumber; i++){
total = total * (inputNumber - i);
}
console.log(inputNumber + '! = ' + total);here is an error i <= inputNumber
should be i < inputNumber
var inputNumber = prompt('Please enter an integer');
var total = 1;
for (i = 0; i < inputNumber; i++){
total = total * (inputNumber - i);
}
console.log(inputNumber + '! = ' + total);you can keep this: i <= inputNumber
and just do this change: total = total * i;
then the code snippet would look like this:
var inputNumber = prompt('Please enter an integer');
var total = 1;
for (i = 1; i <= inputNumber; ++i){
total = total * i;
}
console.log(inputNumber + '! = ' + total);
If you are trying to sum up the numbers, consider using arithmetic series formula. If you're trying to get the factorial, the approach is shown below.
If you want to sum using the loop, just change the *= to +=.
While Loop Approach
const fact = (n) => {
let res = 1;
while (n > 0) {
res *= n;
n--;
}
return res;
}
fact(5) // 120
Do While Approach
const fact = (n) => {
let res = 1;
do {
res *= n;
n--;
} while (n > 0)
return res;
}
fact(3) // 6
That should do the trick. :)
Maybe also considering checking for edge cases like if the n is negative.
Good luck.
While Loop:
const fact=n=>
{
if(n<0) throw 'factorial error on a negative number!'
let r = 1
while(n) r *= n--
return r
}
Do While:
const fact=n=>
{
if(n<0) throw 'factorial error on a negative number!'
let r = 1
do r *= n || 1 // in case of n == 0
while (n--)
return r;
}
complete code
const
msgPrompt_1 = 'Please enter a number from 0 to 100',
msgPrompt_n = 'Try again.... Enter a number 0-100',
fact = n =>
{
let r = 1
while(n) r *= n--
return r
}
let numValue = parseInt(window.prompt(msgPrompt_1, ''), 10)
while(isNaN(numValue) || numValue > 100 || numValue < 0)
{
numValue = parseInt(window.prompt(msgPrompt_n, ''), 10)
}
alert(`factorial value of ${numValue} is = ${fact(numValue)}` )input = i*input; increases input so i < input is always false. Try smth like
var input = parseInt(prompt("Enter the number to get factorial of: "));
var result = input;
for(var i=1;i < input;i++){
result = i * result;
}
document.write(result);
<html>
<head>
<title> New Document </title>
<script type="text/javascript">
function fact(num)
{
var x=parseInt(num);
if(x>0)
x=x* fact(x-1);
alert(x);
}</script>
</head>
<body>
<form name="f1">
Enter the Number :<input type="text" length="8" name="txt1"><br>
<input type="button" value="Find factiorial" onclick="fact(txt1.value)">
</form>
</body>
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, e.g. 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;
}
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 fromatob. 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
productandrange
You have to return the value. Here you go:
function fact(x) {
if(x==0) {
return 1;
}
return x * fact(x-1);
}
function run(number) {
alert(fact(parseInt(number, 10)));
}
and
<input type="button" value="Find factiorial" onclick="run(txt1.value)">
(How to make it work for negative numbers I leave up to you ;) (but I showed in this post anyway))
Just for fun, a more correct, non recursive algorithm:
function fact(x) {
if(x == 0) {
return 1;
}
if(x < 0 ) {
return undefined;
}
if(x === Infinity){
return Infinity
}
for(var i = x; --i; ) {
x *= i;
}
return x;
}
Use loop its easy to implement
function fact(num)
{
if(num<0)
return "Undefined";
var fact=1;
for(var i=num;i>1;i--)
fact*=i;
return fact;
}
<input type="button" value="Find factiorial" onclick="alert(fact(6))">
I have to write a factorial program. There is a hint that says: You solve factorial by multiplying the numbers from 1 all the way up to N together. You need a variable to store the result.
So I think I've done everything right except for storing the result as a variable. What do you guys think?
var N = 5;
function start(){
for(var i = 1; i < N; i++){
print(N *= i);
}
}By the way, the problem was given with N = 5. Thanks for your help!
Calculating a factorial is an aggregate operation, like summing a series.
Here's an example of a function that is specialized to calculate the sum of positive integers up to and including the input.
function sum(n) {
var result = 0;
for (var i = 1; i <= n; i++) {
result += i;
}
return result;
}You can also use a while loop:
function factorial(num)
{
// If the number is less than 0, reject it.
if (num < 0) {
return -1;
}
// If the number is 0, its factorial is 1.
else if (num == 0) {
return 1;
}
var tmp = num;
while (num-- > 2) {
tmp *= num;
}
return tmp;
}
var result = factorial(8); // 40320Or recursion:
function factorial(num)
{
// If the number is less than 0, reject it.
if (num < 0) {
return -1;
}
// If the number is 0, its factorial is 1.
else if (num == 0) {
return 1;
}
// Otherwise, call this recursive procedure again.
else {
return (num * factorial(num - 1));
}
}
var result = factorial(8); // 40320Stolen from MDN: https://msdn.microsoft.com/en-us/library/wwbyhkx4(v=vs.94).aspx