Creating this VCL application consists of the following steps:
- Create a VCL Form with TButton and TComboBox controls.
- Write the code to create strings to the TButton OnClick handler.
- Run the application.
To create a VCL Form with TButton and TComboBox controls
- Choose FileNewOtherDelphi Projects or C++Builder Projects and double-click the VCL Forms Application icon. The VCL Forms Designer is displayed.
- From the Standard page of the Tool palette, place a TButton, a TLabel, and a TComboBox component on the form.
To write the create string procedure
- Select Button1 on the form.
- In the Object Inspector, double-click the OnClick action on the Events tab. The Code Editor displays, with the cursor in the TForm1.Button1Click (Delphi) or TForm1::Button1Click (C++) event handler block.
- For Delphi, place the cursor before the begin reserved word; then press RETURN. This creates a new line above the code block.
- For Delphi, insert the cursor on the new line created and type the following variable declarations:
var
StringList: TStrings;
For C++, enter the following variable declarations:
- Insert the cursor within the code block, and type the following code:
StringList := TStringList.Create;
try
with StringList do begin
Add('Animals');
Add('Cats');
Add('Flowers');
end;
with ComboBox1 do begin
Width := 210;
Items.Assign(StringList);
ItemIndex := 0;
end;
Label1.Caption := 'Flowers has an index of ' +
IntToStr( StringList->IndexOf( 'Flowers' ) );
finally
StringList.free;
end;
StringList = new TStringList();
try {
StringList->Add( “Animals” );
StringList->Add( “Cats” );
StringList->Add( “Flowers” );
ComboBox1–>Width = 210;
ComboBox1–>Items->Assign( StringList );
ComboBox1–>ItemIndex = 0;
Label1–>Caption = “Flowers has an index of “ +
IntToStr( StringList->IndexOf( “Flowers” ) );
} __finally {
StringList->Free();
}
To run the application
- Save your project files; then choose RunRun to build and run the application. The form displays with the controls.
- Click the Button. The strings 'Animals', 'Cars', and 'Flowers' display alphabetically in a list in the ListBox. The Label caption displays the message string: 'Flowers has an index value of 2.'
- In the ComboBox, click the arrow to expand the drop-down list. The strings added in the TButton event handler appear.