CV31 Passing Data Between Multiple Forms

[graytabbycat]

Form 1 5:38
Form 2 6:32

Methods in second form will be called in the first form:
int iRes =
Specify form 2 contains the method and variable.

[graytabbycat]

9.6
*Creating Multiple Forms in a Project*

• Every project that has a form in a Visual C# has a class.
–The default name of the form is Form1 and its class is also named Form1 which is stored in the Form1.cs file.
• A Visual C# project can have multiple forms.
–Each form has its own class that can be instantiated and displayed on the screen.
• When you add additional forms to a project, you add additional classe(s), which are stored in their own files.
• When you create event handler for a specific form's controls, you write them as methods in the form's class.


*Displaying a Form*

• To display a form in your application, you need to create an instance of the form's class. E.g.

ErrorForm myErrorForm = new ErrorForm();

• The above code:
–declares a reference variable named myErrorForm;
–creates an object of the ErrorForm class in memory; and
–assigns a reference to the object to the myErroForm variable.

• After creating the instance, use ShowDialog method
to display the form. E.g.

myErrorForm.ShowDialog();

• The ShowDialog method displays a form on the screen and
it gives that form the focus.


*Accessing Control on a Different Form*

• Controls provided by the .NET Framework have private access by default.
• This means that a control that exists on a particular form can be accessed only by code that is written in that form's
class.
• You can change the access of a control by changing its Modifiers property in the Properties window.
• If you change a control's Modifiers property to Public, the control can be accessed by code outside the form's class.


*Accessing Control on a Different Form*

• For example, suppose GreetingsForm has a Label control named messageLabel, and the messageLabel control's Modifiers property has been set to Public.
• The following code shows how you can create an instance of GreetingsForm, assign a value to the messageLabel control's Text property, and then display the form:

















Modal
and Modeless Forms


•A modal
form or dialog box must be closed or hidden
before you can continue working with the rest of the application.


–When a modal
form is displayed, no other form in the
application can receive the focus until the modal form is closed.


–


•A modeless
form allows the user to switch focus to
another form while it is displayed.


–The user does not have to close a
modeless form to switch focus to another form.


Flow
of Executions