How to write a factorial?

Answer 1

factorial(0) = 0
Test it
double is a mistake. use the following Code:

https://code.sololearn.com/c1eewyI6n2PH/?ref=app

Answer 2

you mean it should be 0 per definition. In my opinion that is wrong, because the factorial of a number is a multiplication from 1 up to the input or from input down to 1. If anybody use an input of 0 or a negativ number, it returns 0. So the return of 0 is an error and no result.
You have posted a link from wikipedia, where is described, that the factorial of 0 ist 0 per definition. But that is (in my opinion) a discrepancy to the definition of the factorial. If you multiply something with 0, the result is 0.

Answer 3

another code here:

https://code.sololearn.com/cR6y0VofOTh7/?ref=app

Answer 4

#include<stdio.h>
#include<string.h>
#include<math.h>
unsigned factorial (int n)
{ if (n==0 || n==1)
return 1 ;
else
return n*(factorial(n-1) );
}
void main ()
{ int n ;
printf("enter a number");
scanf ("%d", &n);
printf ("answer : %d!= %u ",n,factorial(n));
}

Answer 5

https://code.sololearn.com/cTIVoMShX1oV/?ref=app

Answer 6

Use a loop (preferably a for loop) and a variable to store the answer. The variable can be by default 1.
Multiply the variable being incremented in the loop by the answer.
Make the loop continue incrementing by 1 until the number you want the factorial of. The loops variable can start at 2.

Answer 7

int factorial(int n){
if(n<=0) return 1;
return n*factorial(n-1);
}

Answer 8

@Worm why do you return a double? And factorial(0)=1

Answer 9

@Worm Nope factorial(0)=1

https://en.wikipedia.org/wiki/Factorial

www.wolframalpha.com/input/?i=factorial(0)

Answer 10

# Using Python

https://code.sololearn.com/cM4VQXlTNKYF/?ref=app

Answer 11

https://code.sololearn.com/cu00VM8khFtr/?ref=app

Answer 12

https://code.sololearn.com/cq48LPYvoenL/?ref=app
This will help you to solve the factorial problem