date.pas

《Kylix程序设计》一书中附带的例程源代码

unit Date;

interface

uses
  SysUtils;

type
  TMonthType = 1 .. 12;
  TDayType = 1 .. 31;
  TMyDate = class( TObject )
  private
    { Private declarations }
    FYear: Integer;
    FMonth: TMonthType;
    FDay: TDayType;
  public
    { Public declarations }
    constructor Create(); overload;
    constructor Create(
      AYear: Integer; AMonth: TMonthType; ADay: TDayType ); overload;
    function IsLeapYear(): Boolean;
    procedure SetDate(
      AYear: Integer; AMonth: TMonthType; ADay: TDayType );
    procedure GetDate(
      var AYear: Integer; var AMonth: TMonthType; var ADay: TDayType );
    function GetDateAsText(): string;
    procedure Inc();
    procedure Dec();
    destructor Destroy(); override;
  end;

implementation

constructor TMyDate.Create();
begin
  FYear := 2000;
  FMonth := 1;
  FDay := 1;
end;

constructor TMyDate.Create(
  AYear: Integer; AMonth: TMonthType; ADay: TDayType );
begin
  FYear := AYear;
  FMonth := AMonth;
  FDay := ADay;
end;

function TMyDate.IsLeapYear(): Boolean;
begin
  if ( FYear mod 4 <> 0 ) then
    IsLeapYear := false
  else if ( FYear mod 100 <> 0 ) then
    IsLeapYear := true
  else if ( FYear mod 400 <>0 ) then
    IsLeapYear := false
  else
    IsLeapYear := true;
end;

procedure TMyDate.SetDate(
  AYear: Integer; AMonth: TMonthType; ADay: TDayType );
begin
  FYear := AYear;
  FMonth := AMonth;
  FDay := ADay;
end;

procedure TMyDate.GetDate(
  var AYear: Integer; var AMonth: TMonthType; var ADay: TDayType );
begin
  AYear := FYear;
  AMonth := FMonth;
  ADay := FDay;
end;

function TMyDate.GetDateAsText(): string;
begin
  Result := Format( '%4.4d%2.2d%2.2d', [ FYear, FMonth, FDay ] );
end;

procedure TMyDate.Inc();
begin
  case FMonth of
    1, 3, 5, 7, 8, 10:
    begin
      if FDay < 31 then
        System.Inc( FDay )
      else
      begin
        FDay := 1;
        System.Inc( FMonth );
      end;
    end;
    4, 6, 9, 11:
    begin
      if FDay < 30 then
        System.Inc( FDay )
      else
      begin
        FDay := 1;
        System.Inc( FMonth );
      end;
    end;
    2:
    begin
      if IsLeapYear() then
      begin
        if FDay < 29 then
          System.Inc( FDay )
        else
        begin
          FDay := 1;
          System.Inc( FMonth );
        end;
      end
      else
      begin
        if FDay < 28 then
          System.Inc( FDay )
        else
        begin
          FDay := 1;
          System.Inc( FMonth );
        end;
      end;
    end;
    12:
    begin
      if FDay < 31 then
        System.Inc( FDay )
      else
      begin
        FDay := 1;
        FMonth := 1;
        System.Inc( FYear );
      end;
    end;
  end;
end;

procedure TMyDate.Dec();
begin
  case FMonth of
    1:
    begin
      if FDay > 1 then
        System.Dec( FDay )
      else
      begin
        FDay := 31;
        FMonth := 12;
        System.Dec( FYear );
      end;
    end;
    2, 4, 6, 8, 9, 11:
    begin
      if FDay > 1 then
        System.Dec( FDay )
      else
      begin
        FDay := 31;
        System.Dec( FMonth );
      end;
    end;
    3:
    begin
      if IsLeapYear() then
      begin
        if FDay > 1 then
          System.Dec( FDay )
        else
        begin
          FDay := 29;
          System.Dec( FMonth );
        end;
      end
      else
      begin
        if FDay > 1 then
          System.Dec( FDay )
        else
        begin
          FDay := 28;
          System.Dec( FMonth );
        end;
      end;
    end;
    5, 7, 10, 12:
    begin
      if FDay > 1 then
        System.Dec( FDay )
      else
      begin
        FDay := 30;
        System.Dec( FMonth );
      end;
    end;
  end;
end;

destructor TMyDate.Destroy();
begin
  inherited Destroy();
end;

end.