字符串函数

//分割字符串 ExtractStrings
var
  s: String;
  List: TStringList;
begin
  s := 'about: #delphi; #pascal, programming';
  List := TStringList.Create;
  ExtractStrings([';',',',':'],['#',' '],PChar(s),List);
  //第一个参数是分隔符; 第二个参数是开头被忽略的字符

  ShowMessage(List.Text);  //about
                           //delphi
                           //pascal
                           //programming
  List.Free;
end;

//分割字符串的函数,用在不包含空格及特殊字符的情况下，如：'aa a;b bb;ccc;'#13#10'ddd'，复杂的情况用ExtractStrings
procedure Split(const str: string; const c: Char; var List: TStrings);
begin
  List.Clear;
  List.Delimiter := c;
  List.DelimitedText := str;
end;

---

//IsCharAlpha - 是否是个字母

procedure TForm1.Button1Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #65; {A}
  b := IsCharAlpha(c);
  ShowMessage(BoolToStr(b, True)); {True}
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #97; {a}
  b := IsCharAlpha(c);
  ShowMessage(BoolToStr(b, True)); {True}
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #48; {0}
  b := IsCharAlpha(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button4Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #13; {回车键}
  b := IsCharAlpha(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button5Click(Sender: TObject);
var
  c: WideChar;
  b: BOOL;
begin
  c := #19975; {万}
  b := IsCharAlpha(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

---

//IsCharAlphaNumeric - 是否是个文字(字母或数字)  

procedure TForm1.Button1Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #65; {A}
  b := IsCharAlphaNumeric(c);
  ShowMessage(BoolToStr(b, True)); {True}
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #97; {a}
  b := IsCharAlphaNumeric(c);
  ShowMessage(BoolToStr(b, True)); {True}
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #48; {0}
  b := IsCharAlphaNumeric(c);
  ShowMessage(BoolToStr(b, True)); {True}
end;

procedure TForm1.Button4Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #13; {回车键}
  b := IsCharAlphaNumeric(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button5Click(Sender: TObject);
var
  c: WideChar;
  b: BOOL;
begin
  c := #19975; {万}
  b := IsCharAlphaNumeric(c);
  ShowMessage(BoolToStr(b, True)); {True}
end;

---

 //IsCharLower - 是否是个小写字母

procedure TForm1.Button1Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #65; {A}
  b := IsCharLower(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #97; {a}
  b := IsCharLower(c);
  ShowMessage(BoolToStr(b, True)); {True}
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #48; {0}
  b := IsCharLower(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button4Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #13; {回车键}
  b := IsCharLower(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button5Click(Sender: TObject);
var
  c: WideChar;
  b: BOOL;
begin
  c := #19975; {万}
  b := IsCharLower(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

---

 //IsCharUpper - 是否是个大写字母

procedure TForm1.Button1Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #65; {A}
  b := IsCharUpper(c);
  ShowMessage(BoolToStr(b, True)); {True}
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #97; {a}
  b := IsCharUpper(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #48; {0}
  b := IsCharUpper(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button4Click(Sender: TObject);
var
  c: Char;
  b: BOOL;
begin
  c := #13; {回车键}
  b := IsCharUpper(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

procedure TForm1.Button5Click(Sender: TObject);
var
  c: WideChar;
  b: BOOL;
begin
  c := #19975; {万}
  b := IsCharUpper(c);
  ShowMessage(BoolToStr(b, True)); {False}
end;

---

 //CharUpper - 字符或字符串转大写

{对字符}
procedure TForm1.Button1Click(Sender: TObject);
var
  C: Char;
begin
  C := 'a';
  C := Char(CharUpper(PChar(C)));
  ShowMessage(C); {A}
end;

{对字符常量}
procedure TForm1.Button2Click(Sender: TObject);
var
  C: Char;
begin
  C := Char(CharUpper(PChar('a')));
  ShowMessage(C); {A}
end;

{对字符数组}
procedure TForm1.Button3Click(Sender: TObject);
var
  Arr: array[0..2+1] of Char;
begin
  Arr := 'abc';
  CharUpper(Arr);
  ShowMessage(Arr); {ABC}
end;

{对字符串}
procedure TForm1.Button4Click(Sender: TObject);
var
  str: string;
begin
  str := 'abc';
  CharUpper(@str[1]);
  ShowMessage(str); {ABC}
end;

{Delphi 的 System.UpCase 和 SysUtils.LowerCase}
procedure TForm1.Button5Click(Sender: TObject);
var
  c: Char;
  str: string;
begin
  c := 'a';
  c := UpCase(c);

  str := 'abc';
  str := UpperCase(str);

  ShowMessageFmt('%s, %s', [c, str]); {A, ABC}
end;

---

 //CharLower - 字符或字符串转小写

{对字符}
procedure TForm1.Button1Click(Sender: TObject);
var
  C: Char;
begin
  C := 'A';
  C := Char(CharLower(PChar(C)));
  ShowMessage(C); {a}
end;

{对字符常量}
procedure TForm1.Button2Click(Sender: TObject);
var
  C: Char;
begin
  C := Char(CharLower(PChar('A')));
  ShowMessage(C); {a}
end;

{对字符数组}
procedure TForm1.Button3Click(Sender: TObject);
var
  Arr: array[0..2+1] of Char;
begin
  Arr := 'ABC';
  CharLower(Arr);
  ShowMessage(Arr); {abc}
end;

{对字符串}
procedure TForm1.Button4Click(Sender: TObject);
var
  str: string;
begin
  str := 'ABC';
  CharLower(@str[1]);
  ShowMessage(str); {abc}
end;

{Delphi 的 SysUtils.LowerCase}
procedure TForm1.Button5Click(Sender: TObject);
var
  str: string;
begin
  str := 'ABC';
  str := LowerCase(str);
  ShowMessage(str); {abc}
end;

---

 菊子曰：我在用着的博客编辑软件