关于对话框返回字符串的问题！(50分)

我自定义了一个对话框，无论输入什么，返回字符串总为空，感觉应该没问题，真奇怪！
/////////////////
自定义对话框代码
////////////////
unit uInputDialog;

interface

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

type
TfrmNewProject = class(TForm)
edtNewName: TEdit;
GroupBox1: TGroupBox;
bbtnOK: TBitBtn;
bbtnCancel: TBitBtn;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
function InputDialog(DefaultName,NewName:string):Boolean;
end;

var
frmNewProject: TfrmNewProject;

implementation

{$R *.dfm}

procedure TfrmNewProject.FormCreate(Sender: TObject);
begin
bbtnOK.ModalResult:=mrOK;
bbtnCancel.ModalResult:=mrCancel;
end;

function TfrmNewProject.InputDialog(DefaultName,NewName: string): Boolean;
var
frmNewProject:TfrmNewProject;
begin
NewName:=DefaultName;
Result:=False;
frmNewProject:=TfrmNewProject.Create(nil);
edtNewName.Text:=DefaultName;
try
if frmNewProject.ShowModal=mrOk then
begin
NewName:=edtNewName.Text;
Result:=True;
end;
finally
frmNewProject.Free;
end;
end;

end.
///////////////////
主程序调用
////////////////////
procedure TfrmMain.btn1Click(Sender: TObject);
var
AProjectName:string;
begin
if frmNewProject.InputDialog('新工程',AProjectName) then
ShowMessage(AProjectName);

应该把newname返回才行吧,你的AProjectName不是返回值!

To szmh：
那你如何解释下面的ShowOKRightDlg函数，DBName虽然不是返回值，不是也可以当作结果显示出来吗？
procedure TfrmMain.Open1Click(Sender: TObject);
var
DBName: string;
begin
if ShowOKRightDlg('D:/*.mdb', DBName) then ShowMessage(DBName);
end;


//对话框代码如下
unit uOpenPrtDialog;

interface

uses Windows, SysUtils, Classes, Graphics, Forms, Controls, StdCtrls,
Buttons, ExtCtrls, ComCtrls;

type
TOKRightDlg = class(TForm)
OKBtn: TButton;
CancelBtn: TButton;
GroupBox1: TGroupBox;
ListBox1: TListBox;
procedure FormCreate(Sender: TObject);
private
public
procedure GetAllMDB(MDBDir:string);
function GetMDBName:string;
end;

function ShowOKRightDlg(const MDBDir: string
var DBName: string): Boolean;

var
OKRightDlg: TOKRightDlg;

implementation

{$R *.dfm}

function ShowOKRightDlg(const MDBDir: string
var DBName: string): Boolean;
begin
DBName:='';
Result:=False

OKRightDlg:=TOKRightDlg.Create(nil);
try
OKRightDlg.GetAllMDB(MDBDir);
if OKRightDlg.ShowModal=MrOK then
begin
DBName:=OKRightDlg.GetMDBName;
Result:=True;
end;
finally
OKRightDlg.Free;
end;
end;

procedure TOKRightDlg.GetAllMDB(MDBDir: string);
var
SearchRec:TSearchRec;
Path:string;
Attr,Found:integer;
begin
Path:=MDBDir;
Attr:=faAnyFile;
Found:=FindFirst(Path,Attr,SearchRec);
while Found=0 do
begin
ListBox1.Items.Add(SearchRec.Name);
Found:=FindNext(SearchRec);
end;
FindClose(SearchRec);
end;

function TOKRightDlg.GetMDBName:string;
begin
if ListBox1.ItemIndex>=0 then
Result:=ListBox1.Items[ListBox1.ItemIndex];
end;

procedure TOKRightDlg.FormCreate(Sender: TObject);

begin
OKBtn.ModalResult:=mrOK;
CancelBtn.ModalResult:=mrCancel;
end;

end.

小同学，参数要返回，
必须前面加var,
好好复习：过程参数，第一单元，
马上考试了，
少上网，别不及格

谢谢二位大虾指导，我只是个Delphi爱好者，刚学不久，没有系统学过理论，都是从实践入手。不过我在InputDialog方法的NewName参数前加上var后，仍然有问题：无论在edit中输入什么字符串，Application.Message的对话框中都返回“工程“新工程”建立成功！”，而不是随着edit中的内容变化，代码如下：
///////////////////
自定义对话框
///////////////////
unit uInputDialog;

interface

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

type
TfrmNewProject = class(TForm)
edtNewName: TEdit;
GroupBox1: TGroupBox;
bbtnOK: TBitBtn;
bbtnCancel: TBitBtn;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
function InputDialog(const DefaultName:string;var NewName:string):Boolean;{ Public declarations }
end;

var
frmNewProject: TfrmNewProject;

implementation

{$R *.dfm}

procedure TfrmNewProject.FormCreate(Sender: TObject);
begin
bbtnOK.ModalResult:=mrOK;
bbtnCancel.ModalResult:=mrCancel;
end;

function TfrmNewProject.InputDialog(const DefaultName:string;var NewName: string): Boolean;
var
frmNewProject:TfrmNewProject;
begin
NewName:=DefaultName;
Result:=False;
frmNewProject:=TfrmNewProject.Create(nil);
edtNewName.Text:=DefaultName;
try
if frmNewProject.ShowModal=mrOk then
begin
NewName:=edtNewName.Text;
Result:=True;
end;
finally
frmNewProject.Free;
end;
end;

end.
//////////////
主程序调用代码
//////////////
begin
if frmNewProject.InputDialog('新工程',AProjectName) then
begin
Screen.Cursor:=crHourGlass;
if CopyFile(PChar(EXEPath+'ProjectDB/ModelDB/ModelDB.mdb'),PChar(Format(EXEPath+'ProjectDB/%s.mdb',[AProjectName])),False) then
begin
Screen.Cursor:=crDefault;
Application.MessageBox(PChar(Format('工程“%s”建立成功！',[AProjectName])),'新建工程',MB_OK+MB_IconInformation);
end;
end;
end;

function TfrmNewProject.InputDialog(const DefaultName:string;var NewName: string): Boolean;
begin
NewName:=DefaultName;
Result:=False;
frmNewProject:=TfrmNewProject.Create(nil);
frmNewProject.edtNewName.Text:=DefaultName;
try
if frmNewProject.ShowModal=mrOk then
begin
NewName:=frmNewProject.edtNewName.Text;
Result:=NewName<>'';
end;
finally
frmNewProject.Free;
end;
end;

谢谢，看来我犯的都是低级错误，需要好好学习一下基础知识。散分了，分不多，请见量！