Professional C# 7 and .NET Core 2.0, 7th Edition

17Managed and Unmanaged Memory

WHAT’S IN THIS CHAPTER?

• Allocating space on the stack and heap at runtime
• Garbage collection
• Releasing unmanaged resources using destructors and the System.IDisposable interface
• The syntax for using pointers in C#
• Reference semantics
• Using the Span type
• Platform Invoke to access native APIs

WROX.COM CODE DOWNLOADS FOR THIS CHAPTER

The Wrox.com code downloads for this chapter are found at www.wrox.com on the Download Code tab. The source code is also available at https://github.com/ProfessionalCSharp/ProfessionalCSharp7 in the directory Memory.

The code for this chapter is divided into the following major examples:

• PointerPlayground
• PointerPlayground2
• QuickArray
• ReferenceSemantics
• SpanSample
• PlatformInvokeSample

MEMORY

Variables are stored on the stack. The data it references can be on the stack (structs) or on the heap (classes). Structs also can be boxed, so objects on the heap are created. The garbage collector needs to free up unmanaged objects that are no longer needed from the managed heap. Using native APIs, memory can be allocated on the native heap. The garbage collector is not responsible for memory allocated on the native heap. You have to free this memory on your own. There’s a lot to consider with regard to memory.

When you use a managed environment, you can easily be misled to not pay attention to memory management because the garbage collector (GC) deals with that anyway. A lot of work is done by the GC; it’s very ...