CODEWITHSUNDEEP
c#regexregex-greedy
roberto tomás
roberto tomás

Reputation: 4687

C# regex (coming from a perl/javascript background)

This match is giving me no matches, seemingly no matter what:

static String divine(int n)
{
    if (n % 3 == 0) { return String.Join("", Enumerable.Repeat("5", n).ToArray()); }

    String res = String.Join("", Enumerable.Repeat(" ", n));
    Regex ItemRegex = new Regex(@"^(\\s{3}){0,}(\\s{5})*$", RegexOptions.Compiled);
    Match match = ItemRegex.Match(res);

But this PCRE regex is behaving perfectly at regex101.com: ^(\s{3}){0,}(\s{5})*$

It always greedily matches the small group (sets of 3), and matches the large group only as needed to have no spaces unmatched at the end.

My question is, what do I have to do to get the regex to behave as expected in c#? If I had to guess, at this point I am leaning towards {,} maybe being illegal? I don't know.

Upvotes: 0

Views: 45

Answers (1)

Laurel
Laurel

Reputation: 6173

I can see Java's influence. The @ means you do not need the evil escaped escape \\:

@"^(\s{3}){0,}(\s{5})*$"

In case you didn't know, Java's regexes are a pain. Most languages aren't like that. Python, for example, uses r instead of C#'s @.

Edit: JavaScript only makes you escape escapes within strings, but you can use something like: var word2 = word.replace(/\s/g, "");. The syntax is similar to Perl, actually.

Java has no alternative to escaped escapes, which is why I assumed you meant Java.

Upvotes: 2

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