Visual Basic 2005 in a Nutshell, Third Edition

Application Entry Points | 91

Program

Structure

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IL_0000: ldstr "This is a console application."

IL_0005: call void [mscorlib]System.Console::WriteLine(string)

IL_000a: ret

} // end of method StartsHere::Main

The Visual Basic compiler and the .NET Common Language Runtime, it would

seem, have transformed this simple code module into a self-executing class.

Using Main in Windows Forms Applications

All forms displayed in Windows Forms applications must be instantiated before

use. Visual Basic allows you to specify a Form as the startup object of an applica-

tion (instead of a standard Class- or Module-based Main routine), and you don’t

have to add the routine yourself. So is it really there? Yes, the framework adds a

shared Main routine to your class. What does it do? A quick look at the IL gives

the answer. (Lines in this presentation have been wrapped for readability.)

.method public hidebysig static void Main( ) cil managed

{

.entrypoint

.custom instance void

[mscorlib]System.STAThreadAttribute::.ctor( ) = ( 01 00 00 00 )

// Code size 16 (0x10)

.maxstack 8

IL_0000: call class WindowsApplication1.My.MyProject/

MyForms WindowsApplication1.My.MyProject::get_Forms( )

IL_0005: callvirt instance class WindowsApplication1.Form1

WindowsApplication1.My.MyProject/MyForms::get_Form1( )

IL_000a: ...