How can i extract randomstring between A & B. For example:
A randomstring B
7
-
3I cannot speak for others, but I have problems to understand what you want. Can you give a concrete example?Uwe Raabe– Uwe Raabe2012-12-31 09:11:37 +00:00Commented Dec 31, 2012 at 9:11
-
@UweRaabe This should make it more clear :) Strings not chars! :)Nuno Jemaio– Nuno Jemaio2012-12-31 09:13:30 +00:00Commented Dec 31, 2012 at 9:13
-
BTW, one answer will be "regular expressions" because the question contains "extract" and "strings" ;)Uwe Raabe– Uwe Raabe2012-12-31 09:13:53 +00:00Commented Dec 31, 2012 at 9:13
-
@UweRaabe Kein problem ;)Nuno Jemaio– Nuno Jemaio2012-12-31 09:14:17 +00:00Commented Dec 31, 2012 at 9:14
-
1I don't understand your question either. Give a concrete example please.whosrdaddy– whosrdaddy2012-12-31 09:17:54 +00:00Commented Dec 31, 2012 at 9:17
|
Show 2 more comments
3 Answers
Assuming that "randomstring" doesn't contain the enclosing strings "A" or "B", you can use two calls to pos to extract the string:
function ExtractBetween(const Value, A, B: string): string;
var
aPos, bPos: Integer;
begin
result := '';
aPos := Pos(A, Value);
if aPos > 0 then begin
aPos := aPos + Length(A);
bPos := PosEx(B, Value, aPos);
if bPos > 0 then begin
result := Copy(Value, aPos, bPos - aPos);
end;
end;
end;
The function will return an empty string when either A or B are not found.
3 Comments
Jan Doggen
Kudos for answering Uwe, because I still don't understand the question ;-)
LaKraven
I have a recursive version of this which populates a String Array... useful for extracting (for example) all Hyperlinks on a web page's source.
gene b.
Note:
PosEx comes from StrUtilsAnswer with regular expression :)
uses RegularExpressions;
...
function ExtractStringBetweenDelims(Input : String; Delim1, Delim2 : String) : String;
var
Pattern : String;
RegEx : TRegEx;
Match : TMatch;
begin
Result := '';
Pattern := Format('^%s(.*?)%s$', [Delim1, Delim2]);
RegEx := TRegEx.Create(Pattern);
Match := RegEx.Match(Input);
if Match.Success and (Match.Groups.Count > 1) then
Result := Match.Groups[1].Value;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
ShowMessage(ExtractStringBetweenDelims('aStartThisIsWhatIWantTheEnd', 'aStart', 'TheEnd'));
end;
3 Comments
whosrdaddy
@NunoJemaio: the nice thing is that the same pattern would also work for case insensitive search (just add option to TRegEx.Create)
Nuno Jemaio
Will your method work if either the delim is = "" ? For example at the front or end of url's. This works perfect for middle string matching where both delims are not ""
Wayne Barron
This should have been the winning answer. I am stripping tags out of several different brackets and this worked perfectly. Made up a quick demo, from start to a working project, about 5 minutes. THANK YOU!!! Gotta love
RegEx.Another approach:
function ExtractTextBetween(const Input, Delim1, Delim2: string): string;
var
aPos, bPos: Integer;
begin
result := '';
aPos := Pos(Delim1, Input);
if aPos > 0 then begin
bPos := PosEx(Delim2, Input, aPos + Length(Delim1));
if bPos > 0 then begin
result := Copy(Input, aPos + Length(Delim1), bPos - (aPos + Length(Delim1)));
end;
end;
end;
Form1.Caption:= ExtractTextBetween('something?lol/\http','something?','/\http');
Result = lol
1 Comment
Uwe Raabe
This might fail when Delim2 appears before or inside Delim1. If you can exclude this situation, your solution works, too. Btw:
Str is the name of a built-in procedure and should be avoided for variable names.