Unsafe Code and Pointers (C# Programming Guide)

To maintain type safety and security, by default C# does not support pointer arithmetic. However, by using the unsafe keyword, it is possible to define an unsafe context in which pointers can be used. For more information about pointers, see the topic Pointer types.


In the common language runtime (CLR), unsafe code is referred to as unverifiable code. Unsafe code in C# is not necessarily dangerous; it is simply code whose safety cannot be verified by the CLR. The CLR will therefore only execute unsafe code if it is within a fully trusted assembly. If you use unsafe code, it is your responsibility to ensure that your code does not introduce security risks or pointer errors. For more information, see Security and C#.

Unsafe Code Overview

Unsafe code has the following properties:

  • Methods, types, and code blocks can be defined as unsafe.

  • In some cases, unsafe code may increase an application's performance by removing array bounds checks.

  • Unsafe code is required when calling native functions that require pointers.

  • Using unsafe code introduces security and stability risks.

  • In order for C# to compile unsafe code, the application must be compiled with /unsafe.

Related Sections

C# Language Specification

For more information, see the following sections in the C# Language Specification:

  • 18 Unsafe Code

  • B 3 Grammar extensions for unsafe code

See Also

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