TSet

struct Core Since 4.0

#include "Containers/Set.h"

Description

An unordered container of unique elements backed by a hash set. Average-case Add/Contains/Remove are O(1). Use instead of TArray when you need fast membership tests and don't care about order.

Signature

template<typename ElementType, typename KeyFuncs, typename Allocator> class TSet

Caveats & Gotchas

• Elements must be hashable — same requirement as TMap keys.
• No stable iteration order. If order matters, use TArray instead.
• Adding a duplicate element is a no-op — the set silently ignores it.
• Cannot be used as a UPROPERTY without specific type support.

Example

Track visited actors C++

TSet<AActor*> VisitedActors;
VisitedActors.Add(SomeActor);

if (!VisitedActors.Contains(SomeActor))
{
    // first visit
    VisitedActors.Add(SomeActor);
}

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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