regex find exact word/sentences match

Question

I have a linq list with "impportent words" which holds sentences and single words.

I need to find if there is any word or sentences from importent_words which is found in "sentence_to_search_for_importent_word"

At last the result should end up in a array or something.

here is what i done until know..

List<string> importent_words = new List<string>() {"age", "what is", ".", "pages"}

string sentence_to_search_for_importent_words = "what is your age.";

I need to find the importent_words in a sentence and get all the matches outputted to a list

I try this but it does not really do the job

var pattern = new Regex(@"\w+");
var qa = pattern.Split(first_sentence.ToLower()).Where(w => importent_words.Contains(w));

It have to return "age" not "ages" also it should find "what is" not only "what"

With \w it seems to find age but it only output "this" instead of "this is"

It seems like the problem is that "this is" is more than one word.

Are you looking for `importent_words.Where(x => sentence.Contains(x))`? why regex? — Sayse, Jan 11 '17 at 15:28
I would agree, using a regex introduces a second problem, you are not looking for a pattern so a basic check will be ten times better — Jeremy Thompson, Jan 11 '17 at 15:36
i just thought regex was fast, any solution witch is just as good is great too — Glenn Boserup Møller, Jan 11 '17 at 15:39

score 4 · Accepted Answer · edited May 23 '17 at 11:46

4

If all you're looking for is the important words that appear in your sentence then you can just use

importent_words.Where(x => sentence.Contains(x))

If this needs to be case insensitive then you can find a replacement for the Contains(x) from the answers to Case insensitive 'Contains(string)' (or use sentence.ToLower() as you show in your current regex attempt)

edited May 23 '17 at 11:46

Community

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answered Jan 11 '17 at 15:33

Sayse

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Thor · Answer 2 · 2017-01-11T16:01:53.783

0

Just in case you'd like an extendable regex solution. The matches need to be escaped for the regex pattern. You could utilize Regex.Escape() for this.

List<string> importent_words = new List<string>() { "age", "what is", @"\.", "ages", "bob" };
string sentence_to_search_for_importent_words = "what is your age. Frank";
string regexString = string.Join("|" , importent_words.ToArray());
Regex wordRegex = new Regex(regexString);

string[] result = wordRegex.Matches(sentence_to_search_for_importent_words)
    .Cast<Match>()
    .Select(m => m.Value)
    .ToArray();

edited Jan 11 '17 at 16:01

answered Jan 11 '17 at 15:42

Thor

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what does the @"\." do – Glenn Boserup Møller Jan 11 '17 at 17:25
@ before a string in C# escapes the characters so \ will be written as-is. Regex needs to be given \. so that the period is considered as a period but not 'any single character'. – Thor Jan 12 '17 at 09:46
thx alot. made great sence. had never understood the term exscape before in regex. – Glenn Boserup Møller Jan 13 '17 at 00:47

regex find exact word/sentences match

2 Answers2