TArray

class Core Blueprint Since 1.0

#include "Containers/Array.h"

Access: public

Description

The primary dynamic array container in Unreal Engine, equivalent to `std::vector`. Stores elements contiguously in memory. Supports UPROPERTY reflection for Blueprint integration and engine serialization. Provides ordered, random-access storage with amortized O(1) append.

Signature

template <typename InElementType, typename InAllocatorType = FDefaultAllocator> class TArray

Caveats & Gotchas

• TArray is not thread-safe. Protect concurrent access with locks or use thread-safe alternatives.
• Avoid storing raw UObject pointers in TArray across frames — use TArray<TObjectPtr<T>> or TArray<TWeakObjectPtr<T>> to cooperate with GC.
• Reserve() upfront when you know the final size to avoid repeated reallocations.
• Range-based for loops invalidate if you add/remove elements during iteration. Copy first or use a reverse index loop for removal.
• RemoveAt() is O(N) unless you use RemoveAtSwap() which is O(1) but does not preserve order.

Examples

Common TArray operations C++

TArray<int32> Numbers;
Numbers.Reserve(10);         // Preallocate
Numbers.Add(1);
Numbers.Add(2);
Numbers.Add(3);
Numbers.Insert(99, 0);       // Insert at index 0

// Iteration
for (int32 N : Numbers)
{
    UE_LOG(LogTemp, Log, TEXT("%d"), N);
}

// Find
int32 Idx = Numbers.IndexOfByKey(2); // Returns 2 (after insert)
bool bHas = Numbers.Contains(99);    // true

// Remove (preserves order, O(N))
Numbers.Remove(99);

// Sort
Numbers.Sort([](int32 A, int32 B) { return A < B; });

UPROPERTY declaration C++

UPROPERTY(EditAnywhere, BlueprintReadWrite)
TArray<FString> Names;

UPROPERTY()
TArray<TObjectPtr<UMyObject>> ManagedObjects; // GC-safe

Functions (15)

Utility 13 Query 2

Utility

13 ▼

Access	Type	Name	Description
public	function	TArray::Add	Appends an element to the end of the array and returns its index.
public	function	TArray::AddUnique	Adds an element only if it is not already present in the array.
public	function	TArray::ContainsByPredicate	Returns true if any element satisfies the predicate.
public	function	TArray::Emplace	Constructs a new element in-place at the end of the array using the provided constructor arguments.
public	function	TArray::Find	Searches for Item using operator== and returns true if found, setting Index to its position.
public	function	TArray::FindByPredicate	Returns a pointer to the first element for which Pred returns true, or nullptr if none match.
public	function	TArray::Num	Returns the number of elements currently in the array.
public	function	TArray::Remove	Removes all elements equal to Item and returns the number of elements removed.
public	function	TArray::RemoveAll	Removes all elements for which the predicate returns true, preserving order of remaining elements.
public	function	TArray::Reserve	Pre-allocates memory for at least Number elements without changing the logical size.
public	function	TArray::Reset	Removes all elements (calls destructors) but retains allocated memory for reuse.
public	function	TArray::Sort	Sorts the array in-place using an introspective sort (introsort).
public	function	TArray::StableSort	Sorts the array in-place and guarantees that equal elements retain their original relative order.

Query

2 ▼

Access	Type	Name	Description
public	function	TArray::Contains	Returns true if the array contains at least one element equal to Item.
public	function	TArray::IsEmpty	Returns true if the array contains no elements.

Version History

Introduced in: 1.0

Version	Status	Notes
5.6	stable	—
5.0	stable	TObjectPtr support added for UPROPERTY arrays.

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