[SOLVED] Regex search
lazarus / 21-General

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pcurtis · 2021-01-08 07:25

Hi All,

how do I use regex to search for a string within a string?

I am interested in finding if a string contains the following

-pxxxx- where xxxx is an integer 0 to 999999?

Any help please?

Thanks in advance.

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trev · 2021-01-08 10:07

See the Wiki article Regexpr which explains all.

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pcurtis · 2021-01-08 11:30

Not really. It's, like everything else, only a start.

What is the regex to find the "-pxxx-" part

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sstvmaster · 2021-01-08 11:37

Something like this:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Expression
:= '[-p]+[\d]+[-]';or
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Expression
:= '-p+\d+-';

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pcurtis · 2021-01-08 11:57

Looking good! I will test.

Thanks for the regex voodoo.

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Jurassic Pork · 2021-01-08 12:16

hello,
to capture only the digit part of a string you can use a pattern  with
a group capture () for digit like this :
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.Button2Click(Sender: TObject);var     Re1: TRegExpr;begin     
try       re1 := TRegExpr.Create;       re1.Expression := '-p(\d+)-'; 
     if re1.Exec('toto titi  -p239489- tata tutu') then     
 ShowMessage('Result : ' + re1.Match[1]);       finally     
 re1.Free;      end;end;
Friendly, J.P

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Bi0T1N · 2021-01-08 19:41

Actually the regex from Jurassic Pork would match the string from the
first post but also e.g. toto titi  -p239666666666666489- tata tutu.
The line re1.Expression := '-p(\d+)-'; should be changed to
re1.Expression := '-p(\d{4})-'; for a very precise match of only 4
numbers. In case you want to match 4 to 6 numbers use re1.Expression
:= '-p(\d{4,6})-';.
It would also be better to escape the - as \- to avoid unwanted
behaviour: '\-p(\d{4})\-'

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Jurassic Pork · 2021-01-09 06:50

hello,
Quote from: Bi0T1N on January 08, 2021, 08:41:00 pmIt would also be
better to escape the - as \- to avoid unwanted behaviour:
'\-p(\d{4})\-'

Escape only (if wanted) those characters outside character classes:
.^$*+?()[{\|
and these inside character classes (inside brackets []):
^-]\

so you don't need to escape  - in my pattern.

Friendly, J.P