Closures in C# - initating a thread in a function call with a value type

Question

I have this code, which works as I wanted but I don\'t understand exactly why. Thinking about a stack in C, C++, I\'d guess that the p variable will be on the stack on each call

Answer 1

Lambdas are just glorified anonymous delegates

• Rick Strahl (http://www.west-wind.com/weblog/posts/2008/Apr/26/Variable-Scoping-in-Anonymous-Delegates-in-C)

Rick's article describes how the compiler generates a class that handles the enumTest p value and delegate.

Also good info at Where does anonymous function body variables saved ?

Basically the compiler creates a new instance of the "closure class" with local variables that must be passed to lambda. This is why you output is correct.

UPDATE

In the case of:

for (int i=0; i<10; i++) 
{
    var t = new Thread(() => { Console.WriteLine(i); }); 
    t.Start(); 
}

The variable i is shared between the for and the lambda. Each thread is accessing the same i. And since the for loop tends to finsih before any thread runs, all you see is '10'.

See http://msdn.microsoft.com/en-us/library/0yw3tz5k(v=vs.80).aspx