[Solved] How to call a form when there are 3 forms in a project and data Transfer between the forms in C#?

Question

Can you explain why you don’t want to touch your Program.cs file? This is exactly where you change the start-up form.

Change the:

Application.Run(new Form1());

to:

Application.Run(new Form4());

Secondly, you can set the filters on Open- and SaveFileDialog using the Filter property. Set it to a value like this:

XML Files|*.xml

Or for text:

Text Files|*.txt

Edited to add:

To do this from another form:

class Form1 {
  Form2 form2;

  void Form1_Load(object sender, EventArgs e) {
    form2 = new Form2();
  }

  void rdb1_CheckedChanged(object sender, EventArgs e) {
    if (rdb1.Checked) 
      form2.openFileDialog1.Filter = "XML Files|*.xml";
    else
      form2.openFileDialog1.Filter = "Text Files|*.txt";
  }
}

Make sure you have set the Modifiers property of the openFileDialog1 on the Form2 designer to “Public” or “Internal” to allow access to it from outside the class itself.

Accepted Answer