How to open a text file in C#/WinForms/TextBox - mad Editor

Question

I have developed a Text Editor in WinForms. you can download it from here and use it. It works fine. But when I right-click a text file in Windows Explorer and try to open it, it doesn't show it. I have searched solution for this on Web, but failed. Can you suggest a resolution to this. Or should I use RichTextBox. I also tried to create a simple Test project with RichTextBox and used LoadFile().

// Load the contents of the file into the RichTextBox.
richTextBox1.LoadFile(openFile1.FileName, RichTextBoxStreamType.RichText);

This caused a file format error.

Try looking here: http://stackoverflow.com/questions/69761/how-to-associate-a-file-extension-to-the-current-executable-in-c-sharp — Sean Airey, Nov 14 '12 at 11:59
File Association doesn't work. I want to know how to access a file selected in Windows explorer. Thanks — Badar, Nov 14 '12 at 13:02

score 1 · Answer 1 · answered Nov 14 '12 at 11:59

1

The problem is that using:

richTextBox1.LoadFile(openFile1.FileName, RichTextBoxStreamType.RichText);

you have to choose a Rich Text Format (RTF) file, so this is because loading a normal text file gives you a file format error (ArgumentException). So you could load it in this way:

string[] lines = System.IO.File.ReadAllLines(openFile1.FileName);
richTextBox1.Lines = lines;

answered Nov 14 '12 at 11:59

Omar

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Actually my problem is when I right click a text file and click open with this program, then this program should open the text file. In reality an empty text editor is displayed. I have seen on web the solution may be "var args = Environment.GetCommandLineArgs();" but still no success. Trying my best. – Badar Nov 14 '12 at 12:37

score 1 · Answer 2 · edited May 23 '17 at 12:18

Ok so based on your comments and the code provided it won't open the file from windows.

When windows sends a file to a program to open it, it sends it as the first paramater to the exe, e.g. notepad.exe C:\Users\Sean\Desktop\FileToOpen.txt.

You'll need to grab the arguments using Environment.CommandLine or Environment.GetCommandLineArgs().

See here for further info: How do I pass command-line arguments to a WinForms application?

I would handle this in your form's Load event and pass the argument to your function:

string filename = Environment.GetCommandLineArgs()[0];
richTextBox1.LoadFile(filename, RichTextBoxStreamType.RichText);

Also for future reference, if you post an answer saying "This is how I did it" you won't be able to mark it as an answer, essentially leaving the question unanswered. =] — Sean Airey, Nov 14 '12 at 15:03

Badar · Accepted Answer · 2012-11-14T15:20:39.467

I just solved the problem. Thanks for your help.
I am adding answer for future help who face the similar problem.
Here is the solution:

Call the following method from Form_Load():

public void LoadFileFromExplorer()
{
   string[] args = Environment.GetCommandLineArgs();

   if (args.Length > 1)
   {
     string filename1 = Environment.GetCommandLineArgs()[1];
     richTextBox1.LoadFile(filename1, RichTextBoxStreamType.PlainText);
   }
}

To make this work, change Main():

static void Main(String[] args)
    {
        if (args.Length > 0)
        {
            // run as windows app
            Application.EnableVisualStyles();
            Application.Run(new Form1());
        }
        else
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }

How to open a text file in C#/WinForms/TextBox - mad Editor

3 Answers3