Thursday, February 27, 2014

Multiple Main() Method

Multiple Main() Methods

  • As you know already, Main() method is nothing but the entry point of the application.
  • Most commonly, a .NET application contains only one Main() method.
  • If needed, you are supposed to define multiple Main() methods also.
  • But,  at  run  time,  only  one  Main()  method  can  be  specified  as  ―Entry  Point‖.  This specification can be changed using the project properties.
  • To understand better, we start with an example on this
multiple main method

Download above Code of Demo on Multiple Main() Methods : Downloads Links

  • When this program is compiled, the compiler shows 2 compile time errors.
multiple main method
  • It‘s because, two Main() methods are found in MySample  class  and  Program  class; So  that  the  compiler  can‘t  understand  which  Main()  method  is  to  be  used  as  exact entry point.
  • To specify the required entry point, we have to change ―Startup Object‖ option in the project properties.
  • To open the project properties, click on Project menu Properties.
  • Then the project properties will be opened. Now, observe the Startup Object option.
  • The Startup Object option contains two options.
           ---> (Not Set)
           ---> MultipleMainMethods.Program
                   (MultipleMainMethods‖ is the project name).

  • Whenever  it  is  set  to  “(Not  Set)”,  C#  compiler  automatically  detects  the  Main() method, where it is exists. This is the default value in the ―Startup object‖ option. But this fails whenever multiple Main() methods are defined.
  • Now you have to select the required class that contains the desired Main() method as entry point.

multiple main() method

  • Finally close the properties tab and come to ―Program.cs‖ tab.
  • Now run the application.
  • Then you can get the output from the desired Main() method

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