TArray<AActor*> Add

Development Programming & Scripting C++
1

in header:



UPROPERTY(Transient, VisibleAnywhere)	
TArray<AAStar*> stellarBodies;

in BeginPlay:



AAStar* cur = GetWorld()->SpawnActor<AAStar>(AAStar::StaticClass(), FVector::ZeroVector, FRotator::ZeroRotator);
		
stellarBodies.Add(cur);
2

What is the problem you’re having? The Add syntax looks fine.

3

SpawnActor is a templated function, you have to provide whatever class it is in <> brackets

4

I edited my previous post a bit, and updated how i am calling SpawnActor. I noticed that AActor::GetActorClass() is depreciated. Also, i never got a compile error when writing without template params… not sure why.

The error i now get on compile is:



error C2663: 'TArray<AAStar *,FDefaultAllocator>::Add': 2 overloads have no legal conversion for 'this' pointer

Also, in the intellisense for TArray::Add() i see 2 overloads with the following params:


Add(AAStar *const &Item)



Add(AAStar *&&Item)

How am i supposed to read those params? Pointer to a constant address of item? Pointer to an address of an address? What is that? How do i understand that? Coming from C# i hate C++ intellisense, in 90% of the time it is not helpful… and very slow.

I don’t know how to add a simple pointer to my dynamic array of pointers. This is lame…

5

It is likely that the method you are calling stellarBodies.Add(cur) in is const. Can you check that?

6

If the parameter type can be unambiguously deduced, the compiler is happy to use it without an explicit parameter.

7

Check out this for a handy way to decipher some C++:

http://c-faq.com/decl/spiral.anderson.html

AAstar *const &Item is:

“item is a reference to a constant pointer to an AAStar”

Const protects to the left, so the pointer is protected, not Item

8

@Lawlcat: Thanks for the Clockwise/Spiral link, that is very helpful!

My problem is still that i cannot figure out how to add a pointer to my TArray. Would someone be so kind as to just write out how this is done so that i can study how exactly to do this? I have tried multiple ways and nothing seems to work. Thanks

9 


	TArray<AActor*> actorArray;
	TArray<AActor*>* actorArrayReference = &actorArray;

TArray<AActor*> actorArray is a “TArray” containing a list of AActor pointers.

TArray<AActor*>* is a pointer to a TArray containing a list of AActor pointers. We initialize this to the address of (&) actorArray

10

Thanks Lawlcat, i never thought about getting a pointer to the TArray. Although, i still don’t know how to add a pointer into that TArray. For example my code is:



AAStar* const cur = GetWorld()->SpawnActor<AAStar>(AAStar::StaticClass(), FVector::ZeroVector, FRotator::ZeroRotator);
const TArray<AAStar*>* stellarBodiesRef = &stellarBodies;
stellarBodiesRef->Add(&cur);

Also, i am not sure what the pointer to the TArray (stellarBodiesRef) actually gives me as i can call



stellarBodies.Add(XYZ);

without the additional pointer (stellarBodiesRef).

Error on the “add” line. No instance of overloaded function…

11

Also, is there a better way to keep a collection of objects? TArray seems like it is not very easy to work with pointers…

12 

AAStar* cur = GetWorld()->SpawnActor<AAStar>(AAStar::StaticClass(), FVector::ZeroVector, FRotator::ZeroRotator);
TArray<AAStar*> stellarBodiesRef;
stellarBodiesRef.Add(cur);

Try this.

What you store in a container is irrelevant, they are generic. Which container is most suitable will depend on what operations you need to perform on the collection.

13

WHAT?! This compiles:



AAStar* cur = GetWorld()->SpawnActor<AAStar>(AAStar::StaticClass(), FVector::ZeroVector, FRotator::ZeroRotator);
TArray<AAStar*> stellarBodiesRef;
stellarBodiesRef.Add(cur);

but this does not compile:



stellarBodies.Add(cur);

as i have shown in previous posts i have declared stellarBodies and stellarBodiesRef both as TArray<AAStar*>. The only difference is stellarBodies is declared in the header file and stellarBodiesRef is declared locally in the function. Why am i able to add a pointer to one and not the other? stellarBodies is a UPROPERTY… maybe that has something do with it?

the error i get when adding to stellarBodies is:


 error C2663: 'TArray<AAStar *,FDefaultAllocator>::Add': 2 overloads have no legal conversion for 'this' pointer

Also, in the intellisense it says “No instance of overloaded function”

14

I was declaring stellarBodies UPROPERTY as private in the header. Changed it to public, but that didn’t make any difference. Can UPROPERTY be private?

15

WOW! Matt, you are absolutely right. i Was calling stellarBodies.Add(cur) from inside a function marked const. That solves my problem. Thank you!