TArray::RemoveAtSwap
#include "Containers/Array.h"
Access: public
Specifiers: inline
Description
Removes the element at Index by filling its slot with element(s) from the end of the array. O(Count) rather than O(N), but does not preserve element order.
Caveats & Gotchas
- • Element order is NOT preserved — the gap is filled by relocating elements from the tail. Never use this when iteration order or sorted order matters.
- • For a single-element removal (default), one element is moved from the end into the removed slot. For a Count-based removal, as many tail elements as needed are relocated — but the resulting tail region is not necessarily in any meaningful order.
- • The bool bAllowShrinking overload is deprecated in UE 5.6. Use EAllowShrinking::No or EAllowShrinking::Yes.
- • All raw pointers into the array are potentially invalidated even if no reallocation occurs, because the tail element is relocated.
Signature
UE_FORCEINLINE_HINT void RemoveAtSwap(SizeType Index, EAllowShrinking AllowShrinking = UE::Core::Private::AllowShrinkingByDefault<AllocatorType>())Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| Index | SizeType | Index of the element to remove. | — |
| AllowShrinking | EAllowShrinking | Controls whether the backing allocation is shrunk after removal. | UE::Core::Private::AllowShrinkingByDefault<AllocatorType>() |
Return Type
void Example
Order-independent removal from a large pool C++
TArray<AActor*> ActorPool;
// ... populate pool ...
// Remove a dead actor cheaply (O(1), no order needed)
int32 DeadIndex = ActorPool.IndexOfByKey(DeadActor);
if (DeadIndex != INDEX_NONE)
{
ActorPool.RemoveAtSwap(DeadIndex, EAllowShrinking::No);
}Tags
Version History
Introduced in: 4.0
| Version | Status | Notes |
|---|---|---|
| 5.6 | stable | — |
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