Question

I am using C# to find a phrase that may or may not exists in a blog posting. I need to capture the whole sentence that contains the target phrase.

I thought about using the string.contains method but that would return the whole blog post when all I want is the target phrase and its containing sentence.

Example:

I dont want this sentence. I also don't want this setence. But I do want this sentence.

So here the target phrase would be: “I do” and the regex should return the whole containing sentence “But I do want this sentence.”

Thanks.
Aaron

Answer 1

This regex :

resultString = Regex.Match(subjectString, @"(?<=^|\.)[^.]*?(?=\bI do\b).*(\.|$)").Value;

When applied to your input :

I dont want this sentence. I also don't want this setence. But I do want this sentence.

Returns :

But I do want this sentence.

Turn on RegexOptions.Singleline if you worry about multiple lines.