Create and open temporary text file with C# Winforms

Question

I have a winforms app that collects and compiles data and displays on a form. I want a user to be able to click a button that essentially exports that data to a txt file where they can print or save the text file.

I know about using StreamWriter txtFile = File.CreateText(@"C:\path\Foo.txt") and I've used it for generating error logs and stuff, but that may not work because I don't necessarily want to create a new permanent file. Basically, what I'd like is:

User clicks a button, and then Notepad pops up with some info (based off of stuff stored in variables). The user can then decide if they want to save it or print it or whatever. When they close it, they'll be prompted to save (like Notepad always does) and then if they choose not to save, the file just disappears. If I use that above code, I'll end up with a new file created everytime a user clicks that button, which I don't want cuz then my drives will be full of 10,000 text files.

E: Okay, so a couple of people have suggested using this solution:

SendMessage to Notepad++ in C#

But that isn't working for me. I copied the code, dropped in a button, changed the Notepad++ to just Notepad and it's not working. I added in the appropriate using lines. Still not working. I'm not saying that this isn't the solution, I'm just saying that I can't get it to work.

You can save the file to your disk at first then if the user doesn't want to save it, simply delete it. — preciousbetine, Jan 15 '19 at 14:46
Possible duplicate of [SendMessage to Notepad++ in C#](https://stackoverflow.com/questions/42402580/sendmessage-to-notepad-in-c-sharp) — Cid, Jan 15 '19 at 14:47
How about [this](https://stackoverflow.com/a/18465333/43846)? — stuartd, Jan 15 '19 at 14:47
@stuartd link and the duplicate I shown are equivalent. both contains the same solution. — Cid, Jan 15 '19 at 14:48
Maybe just copy it to clipboard: https://stackoverflow.com/questions/3546016/how-to-copy-data-to-clipboard-in-c-sharp — fstam, Jan 15 '19 at 14:50
But as @NathanChampion stated, it's certainly a better option to prompt the user to save or not the file. What if the user doesn't have notepad on the computer ? (Yes, this is possible. Never trust a user.) — Cid, Jan 15 '19 at 14:50

score 2 · Accepted Answer · answered Jan 15 '19 at 15:39

You can do the following, using the clipboard and managing 'notepad.exe' process (it should work for any text editor):

1) Add this reference:

    [DllImport("user32.dll")]
    static extern bool SetForegroundWindow(IntPtr hWnd);

2) Open notepad and paste your data:

public void OpenNotepad()
{
    Clipboard.SetText("All your text");

    Process process = Process.Start("notepad.exe");
    process.WaitForInputIdle();
    SetForegroundWindow(process.MainWindowHandle);
    SendKeys.Send("^V");
}

Beware that this will not create any temporary file, but I assume that is the behavior you want.

This is exactly the behavior I was looking for! Just pop open the dang notepad and fill it with some stuff. Now I just gotta figure out how to do line breaks and stuff with Notepad, which I will. — TnD_Guy, Jan 15 '19 at 15:52

Manoj Choudhari · Answer 2 · 2019-01-15T15:26:08.177

1

First Option: I would suggest to show user a save dialog.

Read Documentation at: https://learn.microsoft.com/en-us/dotnet/framework/winforms/controls/how-to-save-files-using-the-savefiledialog-component

   // Displays a SaveFileDialog so the user can save the Image  
   // assigned to Button2.  
   SaveFileDialog saveFileDialog1 = new SaveFileDialog();  
   saveFileDialog1.Filter = "Text Image|*.txt";  
   saveFileDialog1.Title = "Save the File";  
   saveFileDialog1.ShowDialog();  

   // If the file name is not an empty string open it for saving.  
   if(saveFileDialog1.FileName != "")  
   {   
       /// Write a text file here at path saveFileDialog1.FileName
   }

Second Option (if you still want to stick to temp files):

I would suggest to use temp folder.

   string windowsTempPath = Path.GetTempPath();

   var filePath = Path.Combine(windowsTempPath, "file_" + DateTime.Now.ToFileTimeUtc() + ".txt");

   //// Write txt file

   //// For opening file, use Process.Start
   Process.Start(filePath);

This would launch default program to open the txt file. You will not have any dependency on notepad or notepad++.

Hope this helps.

edited Jan 15 '19 at 15:26

answered Jan 15 '19 at 14:53

Manoj Choudhari

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What assembly or `using` statement am I missing if the `Path` thing isn't working? By the way, in this case, is `Path` a class? I'm still learning what terms (like `Class`) mean. – TnD_Guy Jan 15 '19 at 14:56
Path is in namespace System.IO. It is part of .net framework. – Manoj Choudhari Jan 15 '19 at 14:57
I wanna stick to the temp file thing, but it's not working. It's saying that the `filePath` variable isn't a valid path. – TnD_Guy Jan 15 '19 at 15:24
Did you replace the text inside {curly braces to DateTime.Now.ToFileTimeUTC() ? – Manoj Choudhari Jan 15 '19 at 15:25
I have this code: `var filePath = Path.Combine(windowsTempPath, "file_" + DateTime.Now.ToFileTimeUtc() + ".txt");` and it's not working. Saying that it cannot find the file specified. – TnD_Guy Jan 15 '19 at 15:36
That call does not look for the file existence. There might be some other code which may be breaking. – Manoj Choudhari Jan 15 '19 at 15:39

Create and open temporary text file with C# Winforms

2 Answers2