Question

Inspiried by this example I decided to expand the Factorial class.

using System;
using System.Numerics;

namespace Functions
{
    public class Factorial
    {
        public static BigInteger CalcRecursively(int number)
        {
            if (number > 1)
                return (BigInteger)number * CalcRecursively(number - 1);
            if (number <= 1)
                return 1;

            return 0;
        }

        public static BigInteger Calc(int number)
        {
            BigInteger rValue=1;

            for (int i = 0; i < number; i++)
            {
                rValue = rValue * (BigInteger)(number - i);                
            }

            return rValue;

        }      
    }
}

I’ve used System.Numerics, which isn’t included by default. Therefore, the command
csc /target:library /out:Functions.dll Factorial.cs DigitCounter.cs outputs:

Microsoft (R) Visual C# 2010 Compiler version 4.0.30319.1
Copyright (C) Microsoft Corporation. All rights reserved.

Factorial.cs(2,14): error CS0234: The type or namespace name 'Numerics' does not
        exist in the namespace 'System' (are you missing an assembly reference?)
DigitCounter.cs(2,14): error CS0234: The type or namespace name 'Numerics' does
        not exist in the namespace 'System' (are you missing an assembly
        reference?)
Factorial.cs(8,23): error CS0246: The type or namespace name 'BigInteger' could
        not be found (are you missing a using directive or an assembly
        reference?)
Factorial.cs(18,23): error CS0246: The type or namespace name 'BigInteger' could
        not be found (are you missing a using directive or an assembly
        reference?)
DigitCounter.cs(8,42): error CS0246: The type or namespace name 'BigInteger'
        could not be found (are you missing a using directive or an assembly
        reference?)

OK. I’am missing an assembly reference. I thought “It must be simple. On the whole system should be two System.Numerics.dll files – what I need is to add to the command /link:[Path to the x86 version of System.Numerics.dll] “. The searching results has frozen my soul:

As you can see(or not) there are many more files than I predicted! Moreover, they differ by the size and content. Which one should I include? Why there are five files, although only two have the point of existence? Is the /link:command correct? Or maybe am I totally wrong with my thinking track?

Answer 1

I’ve generally found that using

/r:System.Numerics.dll

lets the compiler just find the assembly in the GAC, which is generally the way you want it. (Certainly it was fine the other day when I needed exactly System.Numerics for a console app…)