Question

When I try this code

public static void Main()
            {
                Console.WriteLine("Total bytes : " + GC.GetTotalMemory(true));

                Console.WriteLine("Total bytes : " + GC.GetTotalMemory(true));

                Console.WriteLine("Total bytes : " + GC.GetTotalMemory(true));

                Console.ReadKey();
            }

I get these results

Why there is a difference between first and rest of the results?

Answer 1

One reason for this would be that your code is translated to something like this:

int totalMemory = GC.GetTotalMemory(true);
string s = "Total bytes : " + totalMemory;
Console.WriteLine(s);

On the second line of the above code, the String class is initialized, if it hasn’t been already. That means its static fields are initialized and its static constructor is called (if it has any). Then the Concat() method is called, and all classes required during its run are initialized too.

And on the third line the Console class is initialized, if it hasn’t been already. Then of course all the classes used during the execution of WriteLine() too.

All the static fields require some memory, so it males sense that when you call GC.GetTotalMemory() for the second time, you get a somewhat higher number.