我的函数没有返回任何东西，但可以编译并且看起来是正确的

Question

Having a hard time trying to figure out why my code doesn't return anything. I want it to return '3628800' as 10! (factorial). Any help is appreciated.

#include <stdio.h>

void ft_iterative_factorial(int nb);

int main()
{
    ft_iterative_factorial(10);
    return 0;
}

void ft_iterative_factorial(int nb)
{
    int i;
    int fact;
    int num;

    fact = 1;
    if (num <= 0)
        fact = 1;
    else
    {
        i = 1;
        while (i <= num)
        {
            fact = fact * i;
            i++;
        }
    }
}

Answer 1

You need to specify a return type, so you would have something like this.

#include <stdio.h>

int ft_iterative_factorial(int nb);

int main()
{
    int num;
    num = ft_iterative_factorial(10);
    return 0;
}

int ft_iterative_factorial(int nb)
{
    int i;
    int fact;
    int num = nb;

    fact = 1;
    if (num <= 0)
        fact = 1;
    else
    {
        i = 1;
        while (i <= num)
        {
            fact = fact * i;
            i++;
        }
    }

   return fact;
}

Answer 2

Hi your function 'ft_iterative_factorial' does not have a return type. Function should have a return type to return some value to the calling function. Also you are not using the passed parameter 'nb' anywhere in your factorial function.

Here is the corrected code:

#include <stdio.h>

//function should have a return value to return something
int ft_iterative_factorial(int nb);

int main()
{
    printf("%d",ft_iterative_factorial(10));
    return 0;
}

int ft_iterative_factorial(int nb)
{
    int i;
    int fact;
    int num = nb;// You have not assigned nb to num
    // In your case num is not initailised

    fact = 1;
    if (num <= 0)
        fact = 1;
    else
    {
        i = 1;
        while (i <= num)
        {
            fact = fact * i;
            i++;
        }
    }
    return fact;
}

Answer 3

If the code compiles, you should simulate the execution of your program step by step:

• the execution enters in main function;
• the execution enters in ft_iterative_factorial , with argument 10 ;
• the variable fact is initialized to 1 ;
• [...] (computations, that seem to be correct);
• the execution leaves ft_iterative_factorial , and therefore discards all variables declared within its scope...

... and here is the problem: the value of fact is lost.

If you want that value to be passed back to main function you should for example declare the function ft_iterative_factorial as

int ft_iterative_factorial(int nb);

and add

return fact;

at the end of its body.

Answer 4

My function isn't returning anything but does compile and seems correct

Your code is not correct at all. In order to check that just print the value of fact inside your ft_iterative_factorial function. By change the return type from void to int , you could solve your return issue but I think you should check the body of ft_iterative_factorial carefully.

Hint::

void ft_iterative_factorial(int nb) //<---change the return type to int
{
    int i;
    int fact;
    int num;

    fact = 1;
    if (num <= 0)  //<-----what is num????? should be nb
        fact = 1;
    else
    {
        i = 1;
        while (i <= num) //<-----what is num????? should be nb
        {
            fact = fact * i;
            i++;
        }
    }
           //<------ just add return statement

}