How do I know what file was opened when someone uses my program with "Open With"?(C#) [duplicate]

This question already has answers here: Handle program being open开发者_Go百科ed by open with? [duplicate] (2 answers) Closed 9 years ago.

I wrote a C# program for converting and re-sizing images. If someone opens a bitmap with my program with "Open With...", how do I "handle" that event and figure out which file they just opened?

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Locate your Main() method

public static void Main(string[] args)
{
   ...
}

the args gets all the command line parameters and the file name should be in there.

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Use System.Environment.GetCommandLineArgs() or String args[] parameter passed to your Main method. The name of the file that is being opened will be there.