Delphi - 在标签之间提取字符串(重复标签)

Question

我正在尝试编写一个函数来提取两个标签之间的字符串。问题是第一个标签在该字符串中是重复的，计数未知，例如

Str := 'Delphi App Hello Hello SomeText here Hello Hello Hello This is a Test!';

我真正想要的是 extract Hello This is a Test!

• TagF 是最后一个Hello 词
• TagL 是测试!

TagF 的重复计数是随机的。

Function sExtractBetweenTagsB(Const s, LastTag, FirstTag: string): string;
var
  i, f : integer;
  sTemp : string;
begin
  sTemp := s;
  repeat
    Delete(sTemp,Pos(FirstTag, sTemp),length(FirstTag));
  until AnsiPos(FirstTag,sTemp) = 0;
  f := Pos(LastTag, sTemp);
  Result:= FirstTag+' '+Copy(sTemp, 1, length(sTemp));
end;

输出是:

Hello Delphi App   SomeText here    This is a Test!

Answer 1

您可以使用 PosEx函数扫描您的字符串以查找标签并向前查找:

program SO30827180;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  SysUtils,
  StrUtils;

function ExtractString(const Input : String; const TagF: String; const TagL : String) : String;

var
  LastPos : Integer;
  NewPos  : Integer;

begin
 Result := '';
 NewPos := Pos(TagF, Input);
 if NewPos <> 0 then
  begin
   LastPos := NewPos;
   // scan to last start tag
   while true do
    begin
     NewPos := PosEx(TagF, Input, NewPos+1);
     if NewPos <> 0 then
      LastPos := NewPos
     else
      Break;
    end;
   // now seek end tag, starting from last starting tag position
   NewPos := PosEx(TagL, Input, LastPos+1);
   if NewPos <> 0 then
    Result := Copy(Input, LastPos, NewPos-LastPos+Length(TagL));
  end;
end;

var
  Line : String;

begin
 Line := 'Delphi App Hello Hello SomeText here Hello Hello Hello This is a Test!';
 Writeln(Format('Input: "%s"', [Line]));
 Writeln(Format('Ouput: "%s"', [ExtractString(Line, 'Hello', 'Test!')]));
 Line := ' Test! Delphi App Hello Hello SomeText here Hello Hello Hello This is a Test! Some end chars';
 Writeln(Format('Input: "%s"', [Line]));
 Writeln(Format('Ouput: "%s"', [ExtractString(Line, 'Hello', 'Test!')]));
 Readln;
end.

示例输出:

Input: "Delphi App Hello Hello SomeText here Hello Hello Hello This is a Test!"
Ouput: "Hello This is a Test!"
Input: " Test! Delphi App Hello Hello SomeText here Hello Hello Hello This is a Test! Some end chars"
Ouput: "Hello This is a Test!"