尝试更改表单时出现程序错误

时间：2012-08-01 00:37:33

标签： delphi delphi-4

我首先创建了一个显示设置的表单。然后我创建了一个登录框，它将从ini文件加载密码。我原本以为加载ini文件时出错了。虽然我在加载设置表单时已将其隔离。这是所有这些代码。

设置屏幕的代码：

    unit Unit1;

interface

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

type

  TForm1 = class(TForm)
    SaveButton: TButton;
    AEditA: TEdit;
    AEditB: TEdit;
    SEditB: TEdit;
    PEditB: TEdit;
    PLabelA: TLabel;
    SLabelA: TLabel;
    ALabelA: TLabel;
    PEditA: TEdit;
    SEditA: TEdit;
    ExitButton: TButton;
    Settings: TLabel;
    ALabelB: TLabel;
    SLabelB: TLabel;
    PLabelB: TLabel;
    AReserveLabel: TLabel;
    BReserveLabel: TLabel;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    Label5: TLabel;
    Label6: TLabel;
    Label8: TLabel;
    Label7: TLabel;
    procedure SaveButtonClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure ExitButtonClick(Sender: TObject);
    procedure AEditAKeyPress(Sender: TObject; var Key: Char);
    procedure AEditBKeyPress(Sender: TObject; var Key: Char);
    procedure SEditAKeyPress(Sender: TObject; var Key: Char);
    procedure SEditBKeyPress(Sender: TObject; var Key: Char);
    procedure PEditAKeyPress(Sender: TObject; var Key: Char);
    procedure PEditBKeyPress(Sender: TObject; var Key: Char);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  IniFile : TIniFile;
  appINI : TIniFile;
  APriceA : String;
  SPriceA : String;
  PPriceA : String;
  APriceB : String;
  SPriceB : String;
  PPriceB : String;

implementation


{$R *.DFM}

procedure TForm1.SaveButtonClick(Sender: TObject);
//Save Button
 begin
  appINI := TIniFile.Create(ChangeFileExt(Application.ExeName,'.ini'));
  APriceA := (AEditA.Text);
  SPriceA := (SEditA.Text);
  PPriceA := (PEditA.Text);
  APriceB := (AEditB.Text);
  SPriceB := (SEditB.Text);
  PPriceB := (PEditB.Text);
  appINI.WriteString('PricesA','Adult',APriceA);
  appINI.WriteString('PricesA','Student',SPriceA);
  appINI.WriteString('PricesA','Pensioner',PPriceA);
  appINI.WriteString('PricesB','Adult',APriceB);
  appINI.WriteString('PricesB','Student',SPriceB);
  appINI.WriteString('PricesB','Pensioner',PPriceB);
  appINI.Free;
  ShowMessage('Settings Saved Successfully!');
 end;

procedure TForm1.FormCreate(Sender: TObject);
//Displays values as the form is created
begin
{ appINI := TIniFile.Create(ChangeFileExt(Application.ExeName,'.ini'));
APriceA := appINI.ReadString('PricesA','Adult','');
SPriceA := appINI.ReadString('PricesA','Student','');
PPriceA := appINI.ReadString('PricesA','Pensioner','');
APriceB := appINI.ReadString('PricesB','Adult','');
SPriceB := appINI.ReadString('PricesB','Student','');
PPriceB := appINI.ReadString('PricesB','Pensioner','');
appINI.Free;
AEditA.Text := (APriceA);
SEditA.Text := (SPriceA);
PEditA.Text := (PPriceA);
AEditB.Text := (APriceB);
SEditB.Text := (SPriceB);
PEditB.Text := (PPriceB);}
end;

procedure TForm1.ExitButtonClick(Sender: TObject);
//Exit Button
begin
Close;
end;

procedure TForm1.AEditAKeyPress(Sender: TObject; var Key: Char);
var s:string;
begin
  s := ('1234567890.'#8); //Add chars you want to allow
  if pos(key,s) =0 then begin
    Key:=#0;
    showmessage('Only Numbers are allowed. Include cents!');
  end;
end;

procedure TForm1.AEditBKeyPress(Sender: TObject; var Key: Char);
var s:string;
begin
  s := ('1234567890.'#8); //Add chars you want to allow
  if pos(key,s) =0 then begin
    Key:=#0;
    showmessage('Only Numbers are allowed. Include cents!');
  end;
end;

procedure TForm1.SEditAKeyPress(Sender: TObject; var Key: Char);
var s:string;
begin
  s := ('1234567890.'#8); //Add chars you want to allow
  if pos(key,s) =0 then begin
    Key:=#0;
    showmessage('Only Numbers are allowed. Include cents!');
  end;
end;

procedure TForm1.SEditBKeyPress(Sender: TObject; var Key: Char);
var s:string;
begin
  s := ('1234567890.'#8); //Add chars you want to allow
  if pos(key,s) =0 then begin
    Key:=#0;
    showmessage('Only Numbers are allowed. Include cents!');
  end;
end;

procedure TForm1.PEditAKeyPress(Sender: TObject; var Key: Char);
var s:string;
begin
  s := ('1234567890.'#8); //Add chars you want to allow
  if pos(key,s) =0 then begin
    Key:=#0;
    showmessage('Only Numbers are allowed. Include cents!');
  end;
end;

procedure TForm1.PEditBKeyPress(Sender: TObject; var Key: Char);
var s:string;
begin
  s := ('1234567890.'#8); //Add chars you want to allow
  if pos(key,s) =0 then begin
    Key:=#0;
    showmessage('Only Numbers are allowed. Include cents!');
  end;
end;
//End of Settings
end.

登录表单的代码：

unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, Mask, inifiles, Unit1;

type
  TForm2 = class(TForm)
    PassEdit: TMaskEdit;
    LoginButton: TButton;
    PassLabel: TLabel;
    InvisiButton: TButton;
    procedure PassEditClick(Sender: TObject);
    procedure LoginButtonClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form2: TForm2;
  IniFile : TIniFile;
  appINI : TIniFile;
  Password : string;

implementation



{$R *.DFM}

procedure TForm2.PassEditClick(Sender: TObject);
begin
PassEdit.Text := '';
end;

procedure TForm2.LoginButtonClick(Sender: TObject);
begin
//if Password = PassEdit.Text then begin
Form2.Hide;
showmessage('test');
Form1.Show;
end;
//end;
procedure TForm2.FormCreate(Sender: TObject);
begin
appINI := TIniFile.Create(ChangeFileExt(Application.ExeName,'.ini'));
Password := appINI.ReadString('Login','Password','');
ShowMessage(Password);
appINI.Free;
end;

end.

这是项目：

program Project1;

uses
  Forms,
  Unit1 in 'Unit1.pas' {Form1},
  Unit2 in 'Unit2.pas' {Form2};


{$R *.RES}

begin
  Application.Initialize;
  //Application.CreateForm(TForm1, Form1);
  Application.CreateForm(TForm2, Form2);
  Application.Run;
end.

1 个答案:

答案 0 :(得分：4)

您已注释掉.dpr file that creates Form1`中的代码行：

  //Application.CreateForm(TForm1, Form1);

但您正在访问Unit1中未创建的表单：

procedure TForm2.LoginButtonClick(Sender: TObject);
begin
//if Password = PassEdit.Text then begin
Form2.Hide;
showmessage('test');
Form1.Show;        // <-- Accessing uncreated form here
end;

取消注释项目文件中的行，以便创建它。请注意，使用Application.CreateForm创建的 first 表单将成为应用程序的主表单，当该表单关闭时，您的应用程序将终止。

您的代码中还有另一个主要缺陷。你不应该从它自己的方法中用名称引用表单本身，就像你在TForm2.LoginButtonClick中所做的那样：

    Form2.Hide;

这意味着如果您重命名该表单，它将无法编译，如果您创建了多个TForm2，您的代码将访问错误的代码或将导致访问非访问权限创建表单（就像你现在遇到的问题）。你应该直接使用表单的方法，比如Hide;' from the method, or use Self.Hide;`来引用当前运行该方法的实例。

（以备将来参考：当你遇到问题时，如果你在解决问题时解释那个问题是有帮助的。“程序错误”没有其他有关错误的信息本身就没有意义。当你输入时“错误”，您应该添加的下一件事是您遇到的完全错误，包括完全错误消息，包括任何地址信息。我们看不到您的错误我们坐在哪里的屏幕，所以我们只提供您提供给我们的信息来帮助您。）

相关问题
最新问题