Regex to extract substrings in C#

Question

I have a string as:

 string subjectString = @"(((43*('\\uth\Hgh.Green.two.190ITY.PCV')*9.8)/100000+('VBNJK.PVI.10JK.PCV'))*('ASFGED.Height Density.1JKHB01.PCV')/476)";

My expected output is:

Hgh.Green.two.190ITY.PCV
VBNJK.PVI.10JK.PCV
ASFGED.Height Density.1JKHB01.PCV

Here's what I have tried:

 Regex regexObj = new Regex(@"'[^\\]*.PCV");
 Match matchResults = regexObj.Match(subjectString);
 string val = matchResults.Value;

This works when the input string is :"@"(((43*('\\uth\Hgh.Green.two.190ITY.PCV')*9.8)/100000+"; but when the string grows and the number of substrings to be extracted is more than 1 , I am getting undesired results .

How do I extract three substrings from the original string?

Wiktor Stribiżew · Accepted Answer · 2017-06-16 08:22:29Z

2

It seems you want to match word and . chars before .PCV.

Use

[\w\s.]*\.PCV

See the regex demo

To force at least 1 word char at the start use

\w[\w\s.]*\.PCV

Optionally, if needed, add a word boundary at the start: @"\b\w[\w\s.]*\.PCV".

To force \w match only ASCII letters and digits (and _) compile the regex object with RegexOptions.ECMAScript option.

Here,

\w - matches any letter, digit or _
[\w\s.]* - matches 0+ whitespace, word or/and . chars
\. - a literal .
PCV - a PCV substring.

Sample usage:

var results = Regex.Matches(str, @"\w[\w\s.]*\.PCV")
    .Cast<Match>()
    .Select(m=>m.Value)
    .ToList();

edited Jun 16, 2017 at 8:22

answered Jun 16, 2017 at 8:06

Wiktor Stribiżew

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5 Comments

BG100 Over a year ago

I think you need to escape the '.' also, like this: [\w\.]*\.PCV

Wiktor Stribiżew Over a year ago

@BG100: No, inside a character class only -, ], \, ^ need escaping. And ] needs no escaping if it is the first char, and ^ needs no escaping if it is not the first char, and - does not need escaping if it is the first/last char in the character class.

BG100 Over a year ago

Ah! I didn't realise that! Just tried it and you're right... :)

user1400915 Over a year ago

@WiktorStribiżew : The results[2] is :"Density.1JKHB01.PCV" but I need "ASFGED.Height Density.1JKHB01.PCV" although the other two results are correct.

Wiktor Stribiżew Over a year ago

Add a whitespace to the class - @"\w[\w\s.]*\.PCV" then. Else, please precise the requirements. I still would follow the whitelisting approach here unless you are sure about what the delimiter pattern should look like.

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