Creating Strings

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Creating this VCL application consists of the following steps:

1. Create a VCL Form with TButton and TComboBox controls.
2. Write the code to create strings to the TButton OnClick handler.
3. Run the application.

To create a VCL Form with TButton and TComboBox controls

1. Choose File > New > Other > Delphi Projects or C++Builder Projects and double-click the VCL Forms Application icon.The VCL Forms Designer is displayed.
2. 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

1. Select Button1 on the form.
2. 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.
3. For Delphi, place the cursor before the begin reserved word; then press RETURN. This creates a new line above the code block.
4. 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:

TStrings *StringList;

5. 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;

For C++

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

1. Save your project files; then choose Run > Run to build and run the application. The form displays with the controls.
2. 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.'
3. In the ComboBox, click the arrow to expand the drop-down list. The strings added in the TButton event handler appear.

See Also

• VCL Overview
• Building a VCL Forms Application