C# 0 The Complete Reference

System.StackOverflowException

 is thrown. Finally, 

stackalloc

can be used only in an unsafe context.

Normally, memory for objects is allocated from the 

heap,

 which is a region of free memory. 

Allocating memory from the stack is the exception. Variables allocated on the stack are not 

garbage-collected. Rather, they exist only while the method in which they are declared is 

executing. When the method is left, the memory is freed. One advantage to using 

stackalloc

 is 

that you don’t need to worry about the memory being moved about by the garbage collector.

Here is an example that uses 

stackalloc

:

// Demonstrate stackalloc.

using System;

class UseStackAlloc {

  unsafe static void Main() {

    int* ptrs = stackalloc int[3];

    ptrs[0] = 1;

    ptrs[1] = 2;

    ptrs[2] = 3;

    for(int i=0; i < 3; i++)

      Console.WriteLine(ptrs[i]);

  }

}

The output is shown here:

1

2

3