Question

I’m trying to exclude some data from a string using regex.

var match = Regex.Match(text, @"^(24 47(.*?)0D 0A)$");

The idea is to filter out and data starting with “24 47” and ending “0D 0A”

The source string:

A0 A1 00 02 83 00 83 0D 0A 
A0 A1 00 02 84 1B 9F 0D 0A 
24 47 50 47 47 41 2C 31 32 31 39 30 37 2E 30 30 30 2C 32 34 30 30 2E 30 30 30 30 2C 4E 2C 31 32 31 30 30 2E 30 30 30 30 2C 45 2C 30 2C 30 30 2C 30 2E 30 2C 30 2E 30 2C 4D 2C 30 2E 30 2C 4D 2C 2C 30 30 30 30 2A 36 35 0D 0A 
24 47 50 47 53 41 2C 41 2C 31 2C 2C 2C 2C 2C 2C 2C 2C 2C 2C 2C 2C 2C 30 2E 30 2C 30 2E 30 2C 30 2E 30 2A 33 30 0D 0A 
24 47 50 52 4D 43 2C 31 32 31 39 30 37 2E 30 30 30 2C 56 2C 32 34 30 30 2E 30 30 30 30 2C 4E 2C 31 32 31 30 30 2E 30 30 30 30 2C 45 2C 30 30 30 2E 30 2C 30 30 30 2E 30 2C 32 38 30 36 30 36 2C 2C 2C 4E 2A 37 34 0D 0A 
24 47 50 56 54 47 2C 30 30 30 2E 30 2C 54 2C 2C 4D 2C 30 30 30 2E 30 2C 4E 2C 30 30 30 2E 30 2C 4B 2C 4E 2A 30 32 0D 0A

But I only want this:

A0 A1 00 02 83 00 83 0D 0A 
A0 A1 00 02 84 1B 9F 0D 0A 

Answer 1

Your regex requires the entire string to start with “24 47” and end with “0D 0A”. You want the multiline option that makes ^ and $ match start/end of each line:

Try

var match = Regex.Match(text, @"^24 47(.*)0D 0A$", RegexOptions.Multiline);

If you want to exclude those lines, then use a negative lookahead:

var match = Regex.Match(text, @"^(?!24 47(.*)0D 0A$).*$", RegexOptions.Multiline);

If you want to find and remove delimited substrings anywhere in a long, contiguous string without line breaks, try this:

resultString = Regex.Replace(subjectString, @"\b24 47(.*?)0D 0A\b", "<removed>");