How to lock a file with C#?

Question

I'm not sure what people usually mean by "lock" a file, but what I want is to do that thing to a file that will produce a "The specified file is in use" error message when I try to open it with another application.

I want to do this to test my application to see how it behaves when I try to open a file that is on this state. I tried this:

FileStream fs = null;  private void lockToolStripMenuItem_Click(object sender, EventArgs e) {     fs = new FileStream(@"C:\Users\Juan Luis\Desktop\corte.txt", FileMode.Open); }  private void unlockToolStripMenuItem_Click(object sender, EventArgs e) {     fs.Close(); } 

But apparently it didn't do what I expected because I was able to open the file with Notepad while it was "locked". So how can I lock a file so it cannot be opened with another application for my testing purposes?

Answer 1

You need to pass in a FileShare enumeration value of None to open on the FileStream constructor overloads:

fs = new FileStream(@"C:\Users\Juan Luis\Desktop\corte.txt", FileMode.Open,      FileAccess.ReadWrite, FileShare.None); 

Answer 2

As per http://msdn.microsoft.com/en-us/library/system.io.fileshare(v=vs.71).aspx

FileStream s2 = new FileStream(name, FileMode.Open, FileAccess.Read, FileShare.None);