Open Windows Form only once in C# [duplicate]

Answer 1

You can just use show\hide methods for opening your form. You also need to initialize all form fields after each time you show this.

Answer 2

Use a boolean variable with default value false which you set to true once the form was shown, and check the variable on form opening.

Answer 3

Before opening the form from your code, check the Application.OpenForms property and see if the form exists in the collection.

Something like:

if ((Application.OpenForms["Form1"] as Form1) != null)
{
 //Form is already open
}
else
{
// Form is not open
}