学步园

TByteHelper

TShortIntHelper

TSmallIntHelper

TWordHelper

TCardinalHelper

TIntegerHelper

TInt64Helper

TUInt64Helper

TNativeIntHelper

TNativeUIntHelper

---

// 它们定义在 System.SysUtils, 功能基本一样, 常用的有:
var
  I: Integer;
  S: string;
begin
  I := I.MaxValue;     //  2147483647
  I := I.MinValue;     // -2147483648
  I := I.Size;         // 4
  I := I.Parse('123'); // 123

  I := 255;
  S := I.ToString();     // '255'
  S := I.ToHexString;    // FF
  S := I.ToHexString(4); // 00FF
end;

---

TBooleanHelper

TByteBoolHelper

TWordBoolHelper

TLongBoolHelper

---

// 它们定义在 System.SysUtils, 基本无用.

---

TSingleHelper

TDoubleHelper

TExtendedHelper

---

// 它们定义在 System.SysUtils, 功能基本一样, 常用的有:
var
  F: Double;
  S: string;
begin
  F := F.MaxValue;      // 1.7976931348623157081e+308
  F := F.MinValue;      // -1.7976931348623157081e+308
  F := F.Size;          // 8
  F := F.Parse('3.14'); // 3.14

  F := Pi * 100;
  s := F.ToString();                      // 314.159265358979
  S := F.ToString(ffExponent, 6, 3);      // 3.14159E+002
  S := F.ToString(ffFixed, MaxInt, 2);    // 314.16; 保留两位小数点; 同 S := Format('%.2f', [F]);
  S := F.ToString(ffCurrency, MaxInt, 4); // ¥314.1593
end;

---

TCharHelper

---

// 它们定义在 System.Character, 它可以彻底替代同单元的 TCharacter 结构体. 主要方法有:
function IsControl: Boolean;
function IsDigit: Boolean;
function IsHighSurrogate: Boolean;
function IsInArray(const SomeChars: array of Char): Boolean;
function IsLetter: Boolean;
function IsLetterOrDigit: Boolean;
function IsLower: Boolean;
function IsLowSurrogate: Boolean;
function IsNumber: Boolean;
function IsPunctuation: Boolean;
function IsSeparator: Boolean;
function IsSurrogate: Boolean;
function IsSymbol: Boolean;
function IsUpper: Boolean;
function IsWhiteSpace: Boolean;
function ToLower: Char;
function ToUpper: Char;
function ToUCS4Char: UCS4Char;

// 以后可以不用 CharInSet()了, 不过得引用 System.Character 单元

uses System.Character;

procedure TForm1.FormCreate(Sender: TObject);
begin
  KeyPreview := True;
end;

procedure TForm1.FormKeyPress(Sender: TObject; var Key: Char);
begin
  if Key.IsInArray(['1', '2', '3', '4', '5', '6', '7', '9', '0']) then
    ShowMessage('按下了数字键');

  if Key.IsNumber then
    ShowMessage('真的按下了数字键');
end;

---

System.SysUtils 还给了一个 TGuidHelper

---

var
  G: TGUID;
  S: string;
  bs: TBytes;
begin
  G := G.NewGuid;
  S := G.ToString;
  bs := G.ToByteArray;
end;

// XE4 中还看到几个 Helper, 如:
TCriticalSectionHelper
TConditionVariableHelper
CFGregorianDateHelper
TD2DMatrix3x2FHelper
TDSSessionHelper
TCanvasHelper
TStyleManagerHelper
TBitmapHelper
TContextHelper
TElementMarginsHelper
TThemeServicesClassHelper

// 这都不常用了, 不过这东西确实方便批量地扩展功能, 这或许会成为写代码的一种基本手法, 譬如:
// System.Rtti 单元中的 TListHelper, TArrayHelper 和 System.Classes 单元中的 TUInt32Helper

---