IsLetter: {是否是个字母; 范围 A..Z 与 a..z}
IsUpper:  {是否是个大写字母; 范围 A..Z}
IsLower:  {是否是个小写字母; 范围 a..z}
IsDigit:  {是否是个十进制数字; 范围 0..9}
IsNumber: {是否是个数字符号; 范围包括 0..9, 还有 ASCII 码中的 178、179、185、188、189、190 等}

测试代码:

unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls;typeTForm1 = class(TForm)Button1: TButton;Button2: TButton;Button3: TButton;Button4: TButton;Button5: TButton;procedure Button1Click(Sender: TObject);procedure Button2Click(Sender: TObject);procedure Button3Click(Sender: TObject);procedure Button4Click(Sender: TObject);procedure Button5Click(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}uses Character;{IsLetter: 是否是个字母}
procedure TForm1.Button1Click(Sender: TObject);
varb1,b2,b3: Boolean;
beginb1 := IsLetter('A'); {是}b2 := IsLetter('a'); {是}b3 := IsLetter('9'); {否}ShowMessageFmt('%s,%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True),BoolToStr(b3,True)]);{True,True,False}b1 := IsLetter('D2009', 1);b2 := IsLetter('D2009', 2);ShowMessageFmt('%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True)]);{True,False}
end;{IsUpper: 是否是个大写字母}
procedure TForm1.Button2Click(Sender: TObject);
varb1,b2,b3: Boolean;
beginb1 := IsUpper('A'); {是}b2 := IsUpper('a'); {否}b3 := IsUpper('9'); {否}ShowMessageFmt('%s,%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True),BoolToStr(b3,True)]);{True,False,False}b1 := IsUpper('Delphi', 1);b2 := IsUpper('Delphi', 2);ShowMessageFmt('%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True)]);{True,False}
end;{IsLower: 是否是个小写字母}
procedure TForm1.Button3Click(Sender: TObject);
varb1,b2,b3: Boolean;
beginb1 := IsLower('A'); {否}b2 := IsLower('a'); {是}b3 := IsLower('9'); {否}ShowMessageFmt('%s,%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True),BoolToStr(b3,True)]);{False,True,False}b1 := IsLower('Delphi', 1);b2 := IsLower('Delphi', 2);ShowMessageFmt('%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True)]);{False,True}
end;{IsDigit: 是否是个十进制数字}
procedure TForm1.Button4Click(Sender: TObject);
varb1,b2,b3: Boolean;
beginb1 := IsDigit('A'); {否}b2 := IsDigit('½'); {否}b3 := IsDigit('9'); {是}ShowMessageFmt('%s,%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True),BoolToStr(b3,True)]);{False,False,True}b1 := IsDigit('D2009', 1);b2 := IsDigit('D2009', 2);ShowMessageFmt('%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True)]);{False,True}
end;{IsNumber: 是否是个数字符号}
procedure TForm1.Button5Click(Sender: TObject);
varb1,b2,b3: Boolean;
beginb1 := IsNumber('A'); {是}b2 := IsNumber('½'); {是}b3 := IsNumber('9'); {否}ShowMessageFmt('%s,%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True),BoolToStr(b3,True)]);{False,True,True}b1 := IsNumber('123¹²³¼½¾', 1);b2 := IsNumber('123¹²³¼½¾', 4); {这里的 9 个字符全都复合}ShowMessageFmt('%s,%s', [BoolToStr(b1,True),BoolToStr(b2,True)]);{True,True}
end;end.