并非所有代码路径都返回值，并且需要从方法中获取2个变量

Question

I'm trying to get newA and newC out of the method but it gives me this error. I also don't know how to separate the numbers if they come out of the method please help, I am still a newbie :( so far the code gets 3 numbers from the user. I then put them into the method and I need to take away newA and newC and store them in separate variables.

namespace factorising_quadratic_expressions
{
    class Program
    {
    static void Main(string[] args)
    {
        int divideBy = 0;
        Console.WriteLine("The form is ax^2 + bx + c"); // all of this is part of my working out.
        Console.WriteLine("Write down a ");
        int a = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("Write down b ");
        int b = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("Write down c ");
        int c = Convert.ToInt32(Console.ReadLine());
        int num = a * c;
        g(num, b, divideBy); // i need to make 2 variables with newA and newC here
    }
    public static int g(int num01, int num02, int num03)
    {
        int x = 0;
        while (x == 0)
        {
            if (num03 > 20)
            {
                Console.WriteLine("this is not possible to factorise");
                x = x + 1;
            }
            num03 = num03 + 1;
            int newA = num01 / num03; //calculations done to get newC and newA
            int newC = num03;
            if (newA + newC == num02)
            {
                x = x + 1;
            }
            else if (newA - newC == num02)
            {
                x = x + 1;
            }
            else if (newC - newA == num02)
            {
                x = x + 1;
            }
            num01 = newC;  //me failing at trying to return them back
            num03 = newA;
            return num01; return num02; return num03;


            }
        }
    }
}

Answer 1

This is because you have no return value outside of your while statement. The compiler thinks that there could potentially be a case where x !== 0 and then the while loop would be skipped. That function is supposed to return an int, so it would cause an error.

Try putting return -1; after the while loop (or some other number that would let you know the function had an error.

Also, there is no need for the multiple return statements at the bottom of your g() function. Once it gets to the first return statement it will return that number and no code after that will run.

If what you're trying to do is print out the answer to the screen, you can make your g() function a void function and not return anything. Right now in your main function, you aren't doing anything with the return values from g() anyway.

Here's how I would write your g() function:

public void g(int num01, int num02, int num03)
{
    if (num03 > 20)
    {
        Console.WriteLine("this is not possible to factorise");
        return;
    }

    num03 = num03 + 1;
    int newA = num01 / num03;
    int newC = num03;

    if (newA + newC == num02)
    {
        return;
    }

    if (newA - newC == num02)
    {
        return;
    }

    if (newC - newA == num02)
    {
        return;
    }

    // Now that we've got all the error cases taken care of,
    // you can do the math here and use console.WriteLine to
    // print it out to the screen.

    return;
}

My apologies if I have any syntax errors in there. I wrote it from memory and didn't try compiling it.