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Question

我能够创建一个名为 speeding.dat 的文件来记录警方测速摄像头记录的罚款信息。包含日期、车辆编号、速度和欠款等信息。但是我不知道如何开发一个子程序，它可以通过提示用户输入车辆登记号并显示该记录中的所有数据来查询文件。

这就是我目前所拥有的......

unit Main;

interface

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

type
  TForm4 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form4: TForm4;
      type
    Tfine = Record
      name : string[15];
      money : String[15];
      date : String[15];
      speed : String[15];
      registration : string[15];
  end;


implementation

{$R *.dfm}


procedure TForm4.FormCreate(Sender: TObject);
var
  myFile   : File of Tfine;
  policeCamera : Tfine;
begin
  AssignFile(myFile, 'speeding.dat');
  ReWrite(myFile);

  policeCamera.name := 'aaa';
  policeCamera.money  := '299.99';
  policeCamera.registration := '123SPY';
  policeCamera.speed := '140';
  policeCamera.Date := '12/01/2001';
    Write(myFile,policeCamera);

  policeCamera.name := 'bbb';
  policeCamera.money  := '299.99';
  policeCamera.registration := 'HELLA';
  policeCamera.speed := '135';
  policeCamera.Date := '12/01/2002';
    Write(myFile,policeCamera);

  policeCamera.name := 'ccc';
  policeCamera.money  := '299.97';
  policeCamera.registration := 'HELLI';
  policeCamera.speed := '145';
  policeCamera.Date := '12/01/2003';
    Write(myFile,policeCamera);

  policeCamera.name := 'ddd';
  policeCamera.money  := '299.96';
  policeCamera.registration := 'HELLL';
  policeCamera.speed := '200';
  policeCamera.Date := '12/01/2004';
    Write(myFile,policeCamera);

  policeCamera.name := 'eee';
  policeCamera.money  := '399.95';
  policeCamera.registration := 'HELLP';
  policeCamera.speed := '310';
  policeCamera.Date := '12/01/2005';
    Write(myFile,policeCamera);

  policeCamera.name := 'fff';
  policeCamera.money  := '199.94';
  policeCamera.registration := 'HELLT';
  policeCamera.speed := '70';
  policeCamera.Date := '12/01/2006';
  Write(myFile,policeCamera);

  CloseFile(myFile);
end;

end.

Answer 1

你想通过车牌号搜索records并显示，试试这个：

Var List : TStringGrid; I : Integer;
    myFile   : File of Tfine;
    policeCamera : Tfine;
    Search : String[15];
begin
List := FindComponent('List') as TStringGrid;
List.Free;
Search := InputBox('Type the registration number:' , 'Search' , '');
 List := TStringGrid.Create(Self);
 With List do
  begin
    Align := alLeft;
    Name := 'List';
    Width := 120*5+20;
    FixedCols :=0;
    FixedRows := 1;
    DefaultColWidth := 120;
    ColCount := 5;
    Parent := Self;
  end;

  List.Cells [0,0] := 'Name';
  List.Cells [1,0] := 'Money';
  List.Cells [2,0] := 'Registration';
  List.Cells [3,0] := 'Speed';
  List.Cells [4,0] := 'Date';
  i := 1;
  AssignFile(myFile , 'speeding.dat');
  Reset(myFile);
  While FilePos(myFile) <> FileSize(myFile) do
    begin
      Read(myFile,policeCamera);
     if policeCamera.registration = Search then
      begin
        List.Cells[0,i] := policeCamera.name;
        List.Cells[1,i] := policeCamera.money;
        List.Cells[2,i] := policeCamera.date;
        List.Cells[3,i] := policeCamera.speed;
        List.Cells[4,i] := policeCamera.registration;
        Inc(i);
      end;
    end;
CloseFile(myFile);
end;