Teach Yourself Borland C++ in 14 Days - portal

The C++Builder IDE Explored: Projects and Forms
7. Change the new form’s Name property to SecondForm and the form’s Caption
property to A Second Form.
8. Choose File | Save from the main menu (or click the Save File button on the
toolbar) and save the file with the name Second.
9. Choose a Label component and drop it on the new form. Change the label’s
Caption property to This is the second form. Change the label’s size and color as
desired. Center the label on the form. Your form should now look roughly similar
to the one in Figure 6.7.
Figure 6.7.
The form up to this
point.
10. Click on the main form. Notice that the second form is covered by the main form.
Double-click the Show Form 2 button. The Code Editor is displayed, and the
cursor is placed just where you need it to begin typing code.
11. Type in code so that the function looks like this (you have to type only one line of
code):
void __fastcall TMainForm::ShowForm2Click(TObject *Sender)
{
SecondForm->ShowModal();
}
12. Run the program.
At this point you will get a compiler error that says Undefined symbol ‘SecondForm’.
Hmmm…SecondForm should be a valid symbol because that’s the name of the second form
we created…I wonder…Aha! Remember that we have two source files with a header for each
source file. The problem is that the MainForm unit can’t see the declaration for the SecondForm
variable (which is a pointer to the TSecondForm class). We have to tell it where to find the class
declaration. (Recall Day 2, “Wading In Deeper.” We have to #include the header for
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