How to match anything but 'just spaces' using .Net Regex

Question

I want to match a string when it contains anything but not 'only spaces'.

Spaces are fine, and can be anywhere as long as there is something else.

I can't seem to get a match when a space appears anywhere.

(EDIT: I am looking to do this in regex as I ultimately want to combine it with other regex patterns using | )

Here is my test code:

class Program
{
    static void Main(string[] args)
    {
        List<string> strings = new List<string>() { "123", "1 3", "12 ", "1  " , "  3", "   "};

        string r = "^[^ ]{3}$";
        foreach (string s in strings)
        {
            Match match = new Regex(r).Match(s);
            Console.WriteLine(string.Format("string='{0}', regex='{1}', match='{2}'", s, r, match.Value));
        }
        Console.Read();
    }
}

Which gives this output:

string='123', regex='^[^ ]{3}$', match='123'
string='1 3', regex='^[^ ]{3}$', match=''
string='12 ', regex='^[^ ]{3}$', match=''
string='1  ', regex='^[^ ]{3}$', match=''
string='  3', regex='^[^ ]{3}$', match=''
string='   ', regex='^[^ ]{3}$', match=''

What I want is this:

string='123', regex='^[^ ]{3}$', match='123' << VALID
string='1 3', regex='^[^ ]{3}$', match='1 3' << VALID
string='12 ', regex='^[^ ]{3}$', match='12 ' << VALID
string='1  ', regex='^[^ ]{3}$', match='1  ' << VALID
string='  3', regex='^[^ ]{3}$', match='  3' << VALID
string='   ', regex='^[^ ]{3}$', match=''    << NOT VALID

Thanks

Grhm · Accepted Answer · 2013-02-12 14:04:18Z

7

I'd use

^\s*\S+.*?$

Breaking down the regex...

^ - start of line
\s* - zero or more whitespace characters
\S+ - one or more non-whitespace characters
.*? - any characters (whitespace or not - non-greedy -> match as few as possible)
$ - end of line.

answered Feb 12, 2013 at 14:04

Grhm

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2 Comments

Ian Campbell Over a year ago

Interesting, thanks @Grhm! It doesn't seem to allow the new-line character \n, should \n* be placed immediately after ^?

Grhm Over a year ago

@Ian Campbell you probably need to add a SingleLine option to make the . character march newlines. See msdn.microsoft.com/en-us/library/…

Daniel Hilgarth · Accepted Answer · 2013-02-12 14:07:02Z

6

No need for a regular expression here. You can use string.IsNullOrWhitespace()

A regular expression is this:

[^ ]

What this does is simple: It checks if your string contains anything that is not a space.

I adjusted your code slightly by adding match.Success to the output:

var strings = new List<string> { "123", "1 3", "12 ", "1  " , "  3", "   ", "" };

string r = "[^ ]";
foreach (string s in strings)
{
    Match match = new Regex(r).Match(s);
    Console.WriteLine(string.Format("string='{0}', regex='{1}', match='{2}', " +
                                    "is match={3}", s, r, match.Value,
                                    match.Success));
}

The result will be:

string='123', regex='[^ ]', match='1', is match=True
string='1 3', regex='[^ ]', match='1', is match=True
string='12 ', regex='[^ ]', match='1', is match=True
string='1  ', regex='[^ ]', match='1', is match=True
string='  3', regex='[^ ]', match='3', is match=True
string='   ', regex='[^ ]', match='', is match=False
string='', regex='[^ ]', match='', is match=False

BTW: Instead of new Regex(r).Match(s) you should use Regex.Match(s, r). This allows the regex engine to cache the pattern.

edited Feb 12, 2013 at 14:07

answered Feb 12, 2013 at 13:47

Daniel Hilgarth

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8 Comments

nuxibyte Over a year ago

Hi Daniel. I would like to use regex here if possible as I'm using regex for some other validation, not just the spaces issue.

Daniel Hilgarth Over a year ago

@errolc: Do you really need the value of the string as part of match.Value? Or is all you are interested in that match.Success is true?

nuxibyte Over a year ago

I just want to know if it matches. I don't care what the value is. I'm using it validate a string. Either its valid according to the regex 'validator'....in which case yay, continue or..... it isnt, barf and exit.

Daniel Hilgarth Over a year ago

In that case, the simple expression from my answer is all you need. It will only match if there is a character other than a space anywhere in your string

nuxibyte Over a year ago

So for this case. A string with something in it would be valid but a blank string would not be.

|

Aasmund Eldhuset · Accepted Answer · 2013-02-12 13:48:11Z

0

What about using ^\s+$ and simply negating the result of Match()?

answered Feb 12, 2013 at 13:48

Aasmund Eldhuset

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2 Comments

nhahtdh Over a year ago

IsMatch() can also be used.

nuxibyte Over a year ago

Thanks to both of you. Time for me to look more closely at the Regex class.

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