TArray::SwapMemory

function Core Since 4.0

#include "Containers/Array.h"

Access: public Specifiers: inline

Description

Swaps two elements by directly exchanging their raw memory bytes via the global Swap template. No bounds checks are performed — this is the low-level implementation called by Swap after it validates the indices.

Caveats & Gotchas

• No bounds checking is performed. Passing out-of-range indices causes undefined behaviour in all build configurations including Debug. Use TArray::Swap if you need the safety checks.
• Swapping the same index with itself is a no-op thanks to the underlying Swap template, but the call overhead is still incurred. Callers that care about performance should check equality before calling.

Signature

UE_FORCEINLINE_HINT void SwapMemory(SizeType FirstIndexToSwap, SizeType SecondIndexToSwap)

Parameters

Name	Type	Description	Default
FirstIndexToSwap	SizeType	Index of the first element to swap.	—
SecondIndexToSwap	SizeType	Index of the second element to swap.	—

Return Type

void

Example

Low-level element swap inside a custom sort partition C++

// Only use SwapMemory when indices are guaranteed valid (e.g. inside a manual sort).
if (Array[PivotIdx] > Array[CompareIdx])
{
    Array.SwapMemory(PivotIdx, CompareIdx);
}

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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