C# Tips: Running External Applications from Windows Forms


Michael Agranov shares some C# Tips for development tasks.

These code samples demonstrate the following development tasks:

  • How to open an external application, such as Microsoft Word.
  • How to open a command prompt in the specified folder, run the command, and redirect the command output to the hosting application.
  • How to open a web browser with a search query.

From the Download section of this tutorial, download the project called ExternalApps. Build and run this application. The following screen shot shows how your application will appear with the Microsoft Word file specified, and after running the command line process.

External Apps Application

Figure 1: External Apps Application

Open Microsoft Word with a Specified File

Your test project contains the TestDocument.docx file in the “..\ExternalApps\bin\Debug” folder. Click on the Specify File button and select TestDocument.docx. After the file name with its complete file path appears in the text box, click the Open in Word button. TestDocument.docx is opened in Microsoft Word.

The following code shows how to retrieve the file name with its complete path and store its value in the text box textBox1. You then use the ProcessStartInfo class property members to specify that you intend to open your test file in Microsoft Word.

private void button1_Click(object sender, EventArgs e)
    OpenFileDialog openFileDialog = new OpenFileDialog();
    openFileDialog.InitialDirectory = Application.StartupPath;
    openFileDialog.Filter = "WORD Files(*.doc;*.docx)|*.doc;*.docx|All Files|*.*";
    if (openFileDialog.ShowDialog() == DialogResult.OK)
        string path = openFileDialog.FileName.ToString();
        textBox1.Text = path;
private void button2_Click(object sender, EventArgs e)
    ProcessStartInfo startInfo = new ProcessStartInfo();
    startInfo.FileName = "WINWORD.EXE";
    startInfo.Arguments = textBox1.Text;

Open Command Prompt in the Specified Folder, Run the Command, and Redirect Output to the Windows Forms Application

Click on the Run Command button. You can see the result of running this application in Figure 1.

The following code shows how to create a command line process that starts in the “c:\” folder, executes the dir command, and redirects the dir command output to the Windows Forms RichTextBox control.

private void button3_Click(object sender, EventArgs e)
    System.Diagnostics.Process process = new System.Diagnostics.Process();
    process.StartInfo.WorkingDirectory = "c:\\";
    process.StartInfo.UseShellExecute = false;
    process.StartInfo.FileName = "cmd.exe";
    process.StartInfo.Arguments = "/c dir";
    process.StartInfo.CreateNoWindow = true;
    process.StartInfo.RedirectStandardInput = true;
    process.StartInfo.RedirectStandardOutput = true;
    process.StartInfo.RedirectStandardError = true;
    string output = process.StandardOutput.ReadToEnd();
    richTextBox1.Text = output;

Open a Web Browser with a URL and a Search Query

Click on the Run Browsers button. As a result of running this application the following happens:

  • The Internet Explorer web browser starts with the www.microsoft.com URL.
  • The Google Chrome web browser starts with the Bing query (“C# examples”).

The following simple code shows how to open browsers.

private void button4_Click(object sender, EventArgs e)
    Process.Start("Chrome.exe", "http://www.bing.com/search?q=C%23+examples");
    Process.Start("IExplore.exe", "www.microsoft.com");

Further Reading and Reference

OpenFileDialog Class

ProcessStartInfo Class

Process Class

Process.Start Method



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