[游戏开发]UE4 C++ 结构体数组使用AddUnique方法添加元素报错

当使用TArray的AddUnique方法给结构体数组添加元素时，如果结构体没有重写==操作符时就会报错，那么为什么会报这个错呢？

因为AddUnique方法在添加元素前会将传入的元素在数组内搜索一遍，也就是Find()函数，在Find函数内部用到了==操作符，但是结构体是自定义的数据类型，所以必须重写==操作符才不会报错。

示例：

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

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "TestActors.generated.h"

UENUM(BlueprintType)
enum class EOrient : uint8
{
	North,
	East,
	South,
	West,
};

USTRUCT(BlueprintType)
struct FATestActor
{
	GENERATED_USTRUCT_BODY()

public:

	UPROPERTY(EditAnyWhere, BlueprintReadWrite)
		FString str;
	UPROPERTY(EditAnyWhere, BlueprintReadWrite)
		EOrient orient;
	UPROPERTY(EditAnyWhere, BlueprintReadWrite)
		float a;
	bool operator==(const FATestActor& ATestActor) const
	{
		return str == ATestActor.str && orient == ATestActor.orient && a == ATestActor.a;
	}
};

UCLASS()
class TESTACTOR_API ATestActors : public AActor
{
	GENERATED_BODY()
	
public:	
	// Sets default values for this actor's properties
	ATestActors();

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

public:	
	// Called every frame
	virtual void Tick(float DeltaTime) override;

public:
	UPROPERTY(EditAnyWhere, BlueprintReadWrite)
		TArray<FATestActor> testArrayStruct;	
};

.cpp
// Fill out your copyright notice in the Description page of Project Settings.
#include "TestActors.h"

// Sets default values
ATestActors::ATestActors()
{
 	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;
}

// Called when the game starts or when spawned
void ATestActors::BeginPlay()
{
	//给自定义结构体的数组添加不重复内容
	FATestActor testActor;
	testActor.str = UTF8_TO_TCHAR("小明");
	testActor.orient = EOrient::East;
	testActor.a = 1.0f;

	FATestActor testActor1;
	testActor1.str = L"小红";
	testActor1.orient = EOrient::East;
	testActor1.a = 1.0f;

	testArrayStruct.AddUnique(testActor);
	testArrayStruct.AddUnique(testActor1);

	Super::BeginPlay();
}

// Called every frame
void ATestActors::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);
}