27 - Unsafe code

Abstract

The core C# language differs from C and C++ in its omission of pointers as a data type. C# provides references and the ability to create objects that are managed by a garbage collector. This design, coupled with other features, makes C# a much safer language than C or C++. In the core C# language, it is simply not possible to have an uninitialized variable, a “dangling” pointer, or an expression that indexes an array beyond its bounds. Whole categories of bugs that routinely plague C and C++ programs are thus eliminated. While practically every pointer type construct in C or C++ has a reference type counterpart in C#, nonetheless, there are situations where access to pointer types becomes a necessity. To address this need, C# provides the ability to write unsafe code. In unsafe code, it is possible to declare and operate on pointers, to perform conversions between pointers and integral types, and to take the address of variables. Unsafe code is a “safe” feature from the perspective of both developers and users. Unsafe code shall be clearly marked with the modifier unsafe, so developers can't possibly use unsafe features accidentally, and the execution engine works to ensure that unsafe code cannot be executed in an untrusted environment.