Cannot use class libraries

Question

Cannot use class libraries

Thomas Olson 0

I am learning how to program in C# using Visual Studio Community 2022 (64-bit). When I build a class library and attempt to call it in a program, the program crashes with a file not found error. (error copied below) I added the dll as a reference and also added the using directive for the library.

text of error:

System.IO.FileNotFoundException

HResult=0x80070002

Message=Could not load file or assembly 'System.Runtime, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

Source=<Cannot evaluate the exception source>

StackTrace:

1 answer

Your answer

Answer 1

Anna Xiu-MSFT 31,056 Microsoft External Staff

Hi @Thomas Olson,

Welcome to Microsoft Q&A!

Could you please tell us how you build a class library and call it in a program?

Which version of System.Runtime did you reference? Please ensure that the version of the referenced ‘System.Runtime’ package is 8.0.0.

Please check your project’s target framework and try to target a different version.

Besides, please check if you have enabled autogenerated binding redirects in the project’s property page or not. You can go to project Properties > Application > check “Auto-generate binding redirects” option. Then, clean and rebuild your solution.

If it persists, please update your VS2022 and create a new project to build it again.

Sincerely,

Anna

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Thomas Olson 0

"Could you please tell us how you build a class library and call it in a program? "

To build/call the library I was using an exercise from a Beginning C# text.

The exercise is creating a Card and Deck class in the library (playing card deck), then adding a console project to the library solution where the console project is "set as startup". The code in the library is:

Card.cs

namespace WpfLibrary2

{

public class Card

{

	public readonly Suit suit;

	public readonly Rank rank;

	public Card(Suit newSuit, Rank newRank)

	{

		suit = newSuit;

		rank = newRank;

	}

	private Card()

	{

	}

	public override string ToString()

	{

		return "The " + rank + " of " + suit + "s";

	}

}

public enum Suit

{

	Club, Diamond, Heart, Spade

}

public enum Rank

{

	Ace = 1,

	Deuce,

	Three,

	Four,

	Five,

	Six,

	Seven,

	Eight,

	Nine,

	Ten,

	Jack,

	Queen,

	King

}

}

and Deck.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace WpfLibrary2

{

public class Deck

{

	private Card[] cards;

	public Deck()

	{

		// public default constructor

		cards = new Card[52];

		for (int suitVal = 0; suitVal < 4; suitVal++)

		{

			for (int rankVal = 1; rankVal < 14; rankVal++)

			{

				cards[suitVal * 13 + rankVal - 1] = new Card((Suit)suitVal, (Rank)rankVal);

			}

		}

	}

	public Card GetCard(int cardNum)

	{

		if (cardNum >= 0 && cardNum <= 51)

			return cards[cardNum];

		else

			throw (new System.ArgumentOutOfRangeException("cardNum", cardNum, "Value must be between ) and 51."));

	}

	public void Shuffle()

	{

		Card[] newDeck = new Card[52];

		bool[] assigned = new bool[52];

		Random sourceGen = new Random();

		for (int i = 0; i < 52; i++)

		{

			int destCard = 0;

			bool foundCard = false;

			while (foundCard == false)

			{

				destCard = sourceGen.Next(52);

				if (assigned[destCard] == false) foundCard = true;

			} // end while foundCard == false

			assigned[destCard] = true;

			newDeck[destCard] = cards[i];

		} // end for int i = 0 to 51

		newDeck.CopyTo(cards, 0);

	}

}

}

The code in the Console app (Program.cs) is:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using WpfLibrary2;

namespace ConsoleApp2

{

// .Net 4.8

public class Program

{

	static void Main(string[] args)

	{

		Console.WriteLine("Starting up.");

		Console.ReadKey();

		Deck myDeck = new Deck();

		myDeck.Shuffle();

		for (int i = 0; i < 52; i++)

		{

			Card tempCard = myDeck.GetCard(i);

			Console.Write(tempCard.ToString());

			if (i != 51)

			{

				Console.Write(",");

			}

			else

			{

				Console.WriteLine();

			}

			Console.ReadKey();

		}

	}

}

}

"Which version of System.Runtime did you reference? Please ensure that the version of the referenced ‘System.Runtime’ package is 8.0.0."

The only place I can determine a System.Runtime version was in the Dependencies for the library. The path shown is:

Path = C:\Program Files\dotnet\packs\Microsoft.NETCore.App.Ref\8.0.10\ref\net8.0\System.Runtime.dll

which does exist.

"Besides, please check if you have enabled autogenerated binding redirects in the project’s property page or not. You can go to project Properties > Application > check “Auto-generate binding redirects” option. Then, clean and rebuild your solution."

Auto-generate binding redirects was already checked and I have done the clean/rebuild without seeing any change.

"If it persists, please update your VS2022 and create a new project to build it again."

I checked and Visual Studio reports that it is up to date.

Anna Xiu-MSFT 31,056 Reputation points Microsoft External Staff

2024-11-12T07:26:20.2866667+00:00

Hello, what is the target framework of your class library project? Please ensure that both projects target the same .NET Framework version.

You can right-click on your solution > Manage NuGet Packages for Solution... >search System.Runtime in the Installed tab > see in which project you have the package installed.

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Cannot use class libraries

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