Error: expression must have pointer type

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#1

I’m using UE 4.15.2

The ‘Barrel’ in the TankAimingComponent is a pointer.

void UTankAimingComponent::AimAt(FVector HitLocation)
{
auto OurTankName = GetOwner()->GetName();
auto BarrelLocation = Barrel->GetComponentLocation()->ToString();
    ...

Barrel-> Should work, but I’m getting an error: “expression must have pointer type”

I’m lost on this one. Why is this complaining that it needs a pointer??? It IS a pointer…

In fact, you can call other member functions of that UStaticMeshComponent in the same manner…

#2

Can you include the code where you created Barrel, probably in the .h file. Also if you are getting the barrel’s location in order to put it in a 

UE_LOG
remember that Unreal requires you to de-reference the the BarrelLocation return value. 
    auto BarrelLocation = Barrel->GetComponentLocation()->ToString();
    UE_LOG(LogTemp, Warning, TEXT(" The barrel location is: %s), *BarrelLocation);
#3

I don’t have issue with dereferencing the variable to get the value. I can’t even compile to make the call in the first place - it’s complaining in the IDE before compile. The Barrel-> is the piece the IDE is complaining about just for that function only. I can call all other Class functions from StaticMeshComponent in the same manner. I’ll paste the code you want in a sec - I’m afk.

#4

Could you post your header and cpp file?

#5

The really weird part is that the compiler thinks Barrel is an FVector…

The very first error is:

expression must have pointer type

then

error C2819: type ‘FVector’ does not have an overloaded member ‘operator ->’

ok - header for TankAimingComponent (.h)

#pragma once

#include "Components/ActorComponent.h"
#include "TankAimingComponent.generated.h"


UCLASS( ClassGroup=(Custom), meta=(BlueprintSpawnableComponent) )
class BATTLETANK_API UTankAimingComponent : public UActorComponent
{
    GENERATED_BODY()

public:	
	// Sets default values for this component's properties
	UTankAimingComponent();

	void AimAt(FVector HitLocation);


	void SetBarrelReference(UStaticMeshComponent* BarrelToSet);

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

public:	
	// Called every frame
	virtual void TickComponent(float DeltaTime, ELevelTick TickType, 
FActorComponentTickFunction* ThisTickFunction) override;

private: 
	UStaticMeshComponent* Barrel = nullptr;
};

and now the CPP file:

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

#include "BattleTank.h"
#include "TankAimingComponent.h"


// Sets default values for this component's properties
UTankAimingComponent::UTankAimingComponent()
{
	// Set this component to be initialized when the game starts, and to be ticked every frame.  You can turn these features
	// off to improve performance if you don't need them.
	PrimaryComponentTick.bCanEverTick = true;

	// ...
}

void UTankAimingComponent::SetBarrelReference(UStaticMeshComponent * BarrelToSet)
{
	Barrel = BarrelToSet;
}

// Called when the game starts
void UTankAimingComponent::BeginPlay()
{
	Super::BeginPlay();

	// ...

}

// Called every frame
void UTankAimingComponent::TickComponent(float DeltaTime, ELevelTick TickType, 
FActorComponentTickFunction* ThisTickFunction)
{
	Super::TickComponent(DeltaTime, TickType, ThisTickFunction);

	// ...
}

void UTankAimingComponent::AimAt(FVector HitLocation)
{
	auto OurTankName = GetOwner()->GetName();
	auto BarrelLocation = Barrel->GetComponentLocation()->ToString();
	UE_LOG(LogTemp, Warning, TEXT("Tank %s aiming at: %s from %s"), *OurTankName, 
*HitLocation.ToString(), *BarrelLocation);
}

Now look, even intellisense “knows” it’s a pointer… !!!

#6

I FOUND THE PROBLEM

oh boy…you’ll love it…

auto BarrelLocation = Barrel->GetComponentLocation()->ToString();

The first error was expression must have pointer type
The second error was type FVector does not have an overloaded member ‘operator’

Now the ‘misleading part’ - the underline for the error is under the ‘Barrel’ variable…

It’s not a problem with the ‘Barrel’ member variable!

The problem is with _the return value for GetComponentLocation()

So the correct code should be:

auto BarrelLocation = Barrel->GetComponentLocation().ToString();

(notice the correct code is:

GetComponentLocation().ToString();

and NOT

GetComponentLocation()->ToString();

and voila… it compiles…

sheesh

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