Entry

Delphi: Constant: Convert: String: How to cast a string to a constant? [shortstring / MethodAddress]

Feb 24th, 2004 19:47
Knud van Eeden,

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--- Knud van Eeden --- 25 February 2004 - 04:40 am -------------------

Delphi: Constant: Convert: String: How to cast a string to a constant? 
[shortstring / MethodAddress]

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Method: parameter passing and using shortstring and a constant string 
parameter

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Steps: Overview:

 1. -Create a new application

 2. -Put a button on the form

 3. -Fill in the following code

--- cut here ---------------------------------------------------------

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, 
Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure PROCTest1;
    procedure PROCTest2( const s : string );
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.PROCTest1;
var s : shortstring;
begin
 s := 'mystring'; // e.g. input this from a data file
 PROCTest2( s );
end;

procedure TForm1.PROCTest2( const s : string );
begin
 ShowMessage( 'here ' + s + ' is a constant string' );
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
 PROCTest1;
end;

end.

--- cut here ---------------------------------------------------------

 4. -Run the code

     That will show a dialog box:

     [here mystring is a constant string]

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