UE4.27 C++ calling DLL

1. First add a x64 dynamic link library in the UE C++ project, name it RouteInterface, and put it under Source;


2. Create two folders under Source, Include and Lisbs, which are used to save the header files of the library And lib file

3. Add a class under the project RouteInterface: TestDll, and save the header file under Include/RouteInterface, and add a header file ExportGlobal.h ExportGlobal.h that imports and exports

symbols

#pragma once

#ifdef ROUTEINTERFACE_EXPORTS
#define EXPORT_LIB __declspec(dllexport)
#else
#define EXPORT_LIB __declspec(dllimport)
#endif

TestDll.h

#pragma once
#include "ExportGlobal.h"

/**
测试使用
*/
class EXPORT_LIB TestDll {
    
    
public:
	int add(int a, int b);
};

TestDll.cpp

#include "pch.h"
#include "RouteInterface/TestDll.h"

int TestDll::add(int a, int b) {
    
    
	return a + b;
}

4. Set the configuration, the header file contains the directory

5. Add [post-generation event]

copy $(TargetPath) $(ProjectDir)..\..\Binaries\Win64\
copy $(OutDir)$(TargetName).lib $(ProjectDir)..\Libs\

6. After compiling, RouteInterface.dll will be generated in: F:\004_Ue4\RotorUAV_26_27\Binaries\Win64 directory
Compilation option: Debug x64

RouteInterface.lib will be generated in F:\004_Ue4\RotorUAV_26_27\Source\Libs directory

7. In UE C++ The project always adds filters, RouteInterface and adds two header files.

8. Add in RotorUAV.Build.cs

using System.IO;

private string ModulePath 
	{
    
    
        get
        {
    
    
			return ModuleDirectory;
        }
	}

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

		/**
		 * PublicIncludePaths为通向此模块内部包含文件的所有路径列表，不向其他模块公开（至少有一个包含到Private路径，
		 * 如果要避免相对路径，则回更多）
		 */
		PublicIncludePaths.Add(Path.Combine(ThirdPartyPath, "..\\include"));
        //附加库列表,PublicAdditionalLibraries是一组包含其他预编译库的列表（.lib文件的名称列表，包含后缀）...
        PublicAdditionalLibraries.Add(Path.Combine(ThirdPartyPath, "RouteInterface.lib"));

Whole file content:

// Copyright Epic Games, Inc. All Rights Reserved.

using UnrealBuildTool;
using System.IO;

public class RotorUAV : ModuleRules { 

	private string ModulePath 
	{
        get
        {
			return ModuleDirectory;
        }
	}

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

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

		PrivateDependencyModuleNames.AddRange(new string[] { "Slate", "SlateCore" });

		// 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

		/**
		 * PublicIncludePaths为通向此模块内部包含文件的所有路径列表，不向其他模块公开（至少有一个包含到Private路径，
		 * 如果要避免相对路径，则回更多）
		 */
		PublicIncludePaths.Add(Path.Combine(ThirdPartyPath, "..\\include"));
        //附加库列表,PublicAdditionalLibraries是一组包含其他预编译库的列表（.lib文件的名称列表，包含后缀）...
        PublicAdditionalLibraries.Add(Path.Combine(ThirdPartyPath, "RouteInterface.lib"));
    }
}

9. Call in the class AMainPlayerController to
include the header file:

#include "../Include/RouteInterface/TestDll.h"

transfer:

	TestDll testDll;
	int32 a = testDll.add(6, 5);

// Fill out your copyright notice in the Description page of Project Settings.


#include "MainPlayerController.h"
#include "Blueprint/UserWidget.h"
#include "../Include/RouteInterface/TestDll.h"

AMainPlayerController::AMainPlayerController() {
    
    

}

//这个宏是为了显示调试信息使用
PRAGMA_DISABLE_OPTIMIZATION

void AMainPlayerController::BeginPlay() {
    
    
	TestDll testDll;
	int32 a = testDll.add(6, 5);

	if (uavMainHUDAsset) {
    
    
		uavMainHUD = CreateWidget<UUserWidget>(this, uavMainHUDAsset);
	}
	uavMainHUD->AddToViewport();
	uavMainHUD->SetVisibility(ESlateVisibility::Visible);

	//鼠标在游戏和界面中同时起作用
	FInputModeGameAndUI gameAndUI;
	SetInputMode(gameAndUI);
	bShowMouseCursor = true;
}

PRAGMA_ENABLE_OPTIMIZATION

Run Options: Developer Editor and Win64

operation result:

aaa