Creating Structs with C++ in Unreal Engine 5

Software Versions: Unreal Engine 5.5.0 | Rider 2024.3

Project Name: MyProject

Structs are great when you want to combine data into one consistent group that multiple classes can utilize. In this example I create a simple FStruct with a name, health, and image that our test players can use.

Creating a new struct wasn't completely clear to me first at first, but to create a new struct, first create a new empty UObject class via the editor or IDE.

With the new empty class I removed everything from both the .h and .cpp files and updated the header file to use USTRUCT() rather than UCLASS() and filled out the macro. I called the struct MyStruct and added a few properties to fill it out. For this example I added a FString for name, a float for health, and UTexture2D that could be used for profile picture.

To keep this simple, I added the constructor in the header file to create some default values. Below is the .h file, the .cpp file is empty.

MyStruct.h

#pragma once

#include "CoreMinimal.h"
#include "UObject/Object.h"
#include "MyStruct.generated.h"

USTRUCT(BlueprintType, Blueprintable)
struct FMyStruct
{
	GENERATED_BODY()

public:
	UPROPERTY(EditAnywhere, BlueprintReadWrite)
	FString Name;
	
	UPROPERTY(EditAnywhere, BlueprintReadWrite)
	float Health;

	UPROPERTY(EditAnywhere, BlueprintReadWrite)
	UTexture2D* Texture;

	// Constructor
	FMyStruct() : Name(TEXT("Default")), Health(100) {}
};

To test out the new struct I created an actor called MyStructPlayer. The actor includes the new struct at the top of the file and uses it to create a new struct using FMyStruct MyStruct. I also added a skeletal mesh to fill out the actor. There's few more things happening in this actor that will be used in a later post regarding UI lists, but now let's just focus on the struct. In the MyStructPlayer constructor is where I set the default values for the struct on the player.

MyStructPlayer.h

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "MyStruct.h"
#include "MyStructPlayer.generated.h"

class USkeletalMeshComponent;
class UWidgetComponent;

UCLASS()
class MYPROJECT_API AMyStructPlayer : public AActor
{
	GENERATED_BODY()

protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;

public:
	// Sets default values for this actor's properties
	AMyStructPlayer();

	UPROPERTY(EditAnywhere)
	USceneComponent* Root;

	UPROPERTY(EditAnywhere)
	USkeletalMeshComponent* SkeletalMesh;

	UPROPERTY(EditAnywhere)
	UWidgetComponent* Widget;
	
	UPROPERTY(EditAnywhere, BlueprintReadWrite)
	FMyStruct MyStruct;
};

MyStructPlayer.cpp

#include "MyStructPlayer.h"
#include "Components/SkeletalMeshComponent.h"
#include "Components/WidgetComponent.h"
#include "MyProject/Widgets/MyWidget_Health.h"

// Sets default values
AMyStructPlayer::AMyStructPlayer()
{
	Root = CreateDefaultSubobject<USceneComponent>(TEXT("Root"));
	Root->bVisualizeComponent = true;
	RootComponent = Root;

	SkeletalMesh = CreateDefaultSubobject<USkeletalMeshComponent>(TEXT("SkeletalMesh"));
	SkeletalMesh->SetupAttachment(RootComponent);

	Widget = CreateDefaultSubobject<UWidgetComponent>(TEXT("Widget"));
	Widget->SetupAttachment(RootComponent);

	MyStruct.Name = TEXT("Name");
	MyStruct.Health = 100.f;
}

Although this is a basic example, using structs can be useful to ensure data is consistent across multiple classes. This struct is being used in the project's gym where I tie to values to a widget.