Issues with linking static libraries in UE4. Would appreciate any help from anyone who has linked a static library in UE4 4.16!

Development Programming & Scripting
1

Hi,

I am following this tutorial ( link ) which shows how to link a static library. To be sure it is not my library that is causing an issue I have created the example library in the MSDN tutorial. The library simply has a functions which sums two inputs and returns a double. I have tested the library in a c++ project (no UE4) and it works fine.

When I follow the steps and make the changes (shown below) to the build.cs file I get errors. The changes to the build.cs file are simply copy paste from the tutorial with necessary function names changed. My code can have the #include without errors but whenever I try to call a function it does not work. I would really appreciate any help.

If anyone has linked a static library in 4.16 is there any chance you could paste your build.cs to see how you have done it. I think the tutorial is only for pre 4.15.

using System.IO;
using UnrealBuildTool;

public class TheTable : ModuleRules
{

	public TheTable(ReadOnlyTargetRules Target) : base(Target)
	{
		PCHUsage = PCHUsageMode.UseExplicitOrSharedPCHs;
	
		PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore" });

		PrivateDependencyModuleNames.AddRange(new string[] {  });

		// Uncomment if you are using Slate UI
		// PrivateDependencyModuleNames.AddRange(new string[] { "Slate", "SlateCore" });
		
		// Uncomment if you are using online features
		// PrivateDependencyModuleNames.Add("OnlineSubsystem");

		// To include OnlineSubsystemSteam, add it to the plugins section in your uproject file with the Enabled attribute set to true
	}

    private string ModulePath
    {
        get { return ModuleDirectory; }
    }

    private string ThirdPartyPath
    {
        get { return Path.GetFullPath(Path.Combine(ModulePath, "../ThirdParty/")); }
    }

    public TheTable(TargetInfo Target)
    { 
        LoadBobsMagic(Target);
    }

    public bool LoadBobsMagic(TargetInfo Target)
    {
        bool isLibrarySupported = false;

        if ((Target.Platform == UnrealTargetPlatform.Win64) || (Target.Platform == UnrealTargetPlatform.Win32))
        {
            isLibrarySupported = true;

            string PlatformString = (Target.Platform == UnrealTargetPlatform.Win64) ? "x64" : "x86";
            string LibrariesPath = Path.Combine(ThirdPartyPath, "MathFuncsLib", "Libraries");

            /*
            test your path with:
            using System; // Console.WriteLine("");
            Console.WriteLine("... LibrariesPath -> " + LibrariesPath);
            */

            PublicAdditionalLibraries.Add(Path.Combine(LibrariesPath, "MathFuncsLib." + PlatformString + ".lib"));
        }

        if (isLibrarySupported)
        {
            // Include path
            PublicIncludePaths.Add(Path.Combine(ThirdPartyPath, "MathFuncsLib", "Includes"));
        }

        Definitions.Add(string.Format("WITH_BOBS_MAGIC_BINDING={0}", isLibrarySupported ? 1 : 0));

        return isLibrarySupported;
    }

}

Here is the code I am am calling (within a component of a pawn):

double UGetDataForRL::testlibs(double a, double b)
{
	double test = MathFuncs::MyMathFuncs::Add(a, b);
	return test;
}

The errors i get are:

Warning CS0618 ‘UnrealBuildTool.ModuleRules.ModuleRules()’ is obsolete: ‘Please change your module constructor to take a ReadOnlyTargetRules parameter, and pass it to the base class constructor (eg. “MyModuleRules(ReadOnlyTargetRules Target) : base(Target)”).’ TheTable c:\Users\Documents\Unreal Projects\03_BuildingEscape\TheTable\Source\TheTable\TheTable.Build.cs 36

Warning Module constructors should take a ReadOnlyTargetRules argument (rather than a TargetInfo argument) and pass it to the base class constructor from 4.15 onwards. Please update the method signature. TheTable C:\Users\Documents\Unreal Projects\03_BuildingEscape\TheTable\Source\TheTable\TheTable.Build.cs 1

Error LNK2019 unresolved external symbol “public: static double __cdecl MathFuncs::MyMathFuncs::Add(double,double)” (?Add@MyMathFuncs@MathFuncs@@SANNN@Z) referenced in function “public: double __cdecl UGetDataForRL::testlibs(double,double)” (?testlibs@UGetDataForRL@@QEAANNN@Z) TheTable C:\Users\Documents\Unreal Projects\03_BuildingEscape\TheTable\Intermediate\ProjectFiles\GetDataForRL.cpp.obj 1

Error LNK1120 1 unresolved externals TheTable C:\Users\Documents\Unreal Projects\03_BuildingEscape\TheTable\Binaries\Win64\UE4Editor-TheTable-5513.dll 1

Error Failed to produce item: C:\Users\Documents\Unreal Projects\03_BuildingEscape\TheTable\Binaries\Win64\UE4Editor-TheTable-5513.dll TheTable C:\Users\Documents\Unreal Projects\03_BuildingEscape\TheTable\Intermediate\ProjectFiles\ERROR 1

Error MSB3075 The command ““C:\Program Files\Epic Games\UE_4.16\Engine\Build\BatchFiles\Build.bat” TheTableEditor Win64 Development “C:\Users\Documents\Unreal Projects\03_BuildingEscape\TheTable\TheTable.uproject” -waitmutex” exited with code 5. Please verify that you have sufficient rights to run this command. TheTable C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\VC\VCTargets\Microsoft.MakeFile.Targets 44

2

Remove:

     public TheTable(TargetInfo Target)
     { 
         LoadBobsMagic(Target);
     }

and add:

LoadBobsMagic(Target);

To:

public TheTable(ReadOnlyTargetRules Target) : base(Target)
3

I love you.