Picking certain strings of an array with C#

Question

I am trying to pick paticular strings in an array and add them to a new array e.g. I want to grab all strings in the array that contain .txt and .rtf and add them to a new array e.g. filteredStrings[]

Do you HAVE to use regex? Would be much simpler to simply use String.Contains — Jimmy D
– Jimmy D, Commented Jan 31, 2012 at 14:21

Sergey Kalinichenko · Accepted Answer · 2012-01-31 14:22:04Z

7

You do not need regex for something that simple: Contains works faster, and is easier to understand:

var filteredStrings = myStrings.Where(s => s.Contains(".txt") || s.Contains(".rtf")).ToArray();

If you insist on using regex, you can do this:

var regexp = new Regex("[.](txt|rtf)");
var filteredStrings = myStrings.Where(s => regexp.IsMatch(s)).ToArray();

answered Jan 31, 2012 at 14:22

Sergey Kalinichenko

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6 Comments

mikus Over a year ago

however regex could be more flexible

tenfour Over a year ago

A plugin system would be more flexible; until you need that flexibility don't introduce the burden.

Till Over a year ago

Since they seem to be file extensions it might be a good idea to use the String.EndsWith() method.

Sergey Kalinichenko Over a year ago

@Till absolutely, if the OP is indeed talking about file extensions (which I am 99% certain that he does) then EndsWith is a preferred choice.

Mike Over a year ago

Error 1 'System.Array' does not contain a definition for 'Where' and no extension method 'Where' accepting a first argument of type 'System.Array' could be found –

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spender · Accepted Answer · 2012-01-31 14:23:05Z

1

myArray.Where(x => Regex.IsMatch(x, @"\.(txt|rtf)$")).ToArray()

answered Jan 31, 2012 at 14:23

spender

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2 Comments

Mike Over a year ago

Error 1 'System.Array' does not contain a definition for 'Where' and no extension method 'Where' accepting a first argument of type 'System.Array' could be found

AlanT Over a year ago

@Mike What version of .Net are you using? If 3.5 or later you just need to add Using System.Linq to you file. If older, then is it possible for you to update to 3.5 or higher?

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