Version: 2023.2
LanguageEnglish
  • C#

NativeArray<T0>.UnsafeElementAt

Suggest a change

Success!

Thank you for helping us improve the quality of Unity Documentation. Although we cannot accept all submissions, we do read each suggested change from our users and will make updates where applicable.

Close

Submission failed

For some reason your suggested change could not be submitted. Please <a>try again</a> in a few minutes. And thank you for taking the time to help us improve the quality of Unity Documentation.

Close

Cancel

Declaration

public ref readonly T UnsafeElementAt(int index);

Parameters

index Index of the element.

Returns

T A ref readonly to a value of type T.

Description

Read-only access to NativeArray.ReadOnly elements by index.

This method is dangerous because it returns reference to the memory that can be destroyed (with Dispose, for instance) and if the ref local is accessed that could lead to undefined results including crash.

public readonly struct BigStruct
{
    public readonly long a;
    public readonly long b;
    public readonly long c;
    public readonly long d;
}

static void ProcessByte(byte b) { ... }

static void ProcessBigStructWithoutCopy(in BigStruct bigStruct) // see 'in' modificator { ... }

static void Example() { const int n = 32;

var nativeArrayOfBytes = new NativeArray<byte>(n, Allocator.Temp); var nativeArrayOfBigStructures = new NativeArray<FixedString4096Bytes>(n, Allocator.Temp);

// ... fill the arrays with some data ...

var readOnlyBytes = nativeArrayOfBytes.AsReadOnly(); for (var i = 0; i < n; ++i) { ProcessByte(readOnlyBytes[i]); //ProcessByte(readOnlyBytes.UnsafeElementAt(i)); is more expensive, since pointer on x64 platforms is 8 times bigger than a byte }

var readOnlyBigStructures = nativeArrayOfBigStructures.AsReadOnly(); for (var i = 0; i < n; ++i) { //ProcessBigStructWithoutCopy(readOnlyBigStructures[i]); copy - expensive in this case ProcessBigStructWithoutCopy(readOnlyBigStructures.UnsafeElementAt(i)); }

// dangerous part ref var element = ref readOnlyBigStructures.UnsafeElementAt(4);

// element is valid here ProcessBigStructWithoutCopy(element);

nativeArrayOfBigStructures.Dispose();

// access to element here is undefined, can lead to a crash or wrong results // ProcessBigStructWithoutCopy(element); <-- do not do this! }