Can Regex Extract Multiple Numbers from String?

Question

Let's say I have a string like:

SORT_123_456

Is there an easy way to parse the two integer values? I do not know how many digits these values will have. It would also be helpful if I could validate the other characters and just abandon the parsing if they don't appear as I have them above (that would indicate something is wrong).

I know I can parse character by character, but I was wondering if Regex could handle this.

I just haven't really used regular expressions. Can someone tell me if this can be done more easily using Regex?

Yes, just like I have it above except for the exact digits. And if it isn't "_" delimited, then I just abandon parsing because something would be very wrong. — Jonathan Wood
– Jonathan Wood, Commented Sep 3, 2014 at 17:59
you could have used the split() function and then check to see if you have 3 elements in the array that are loaded if string[0] = "" then you know that the word SORT_ was missing — MethodMan
– MethodMan, Commented Sep 3, 2014 at 18:06
I posted an example using Split Function as well so that you could also reference or try if you are not too familiar with using RegEx — MethodMan
– MethodMan, Commented Sep 3, 2014 at 18:15

user3398633 · Accepted Answer · 2014-09-03 17:59:50Z

6

SORT_(\d+)_(\d+) will do it. Just extract the two groups after using your regex.

If SORT is remplaced by an other word, then \w+_(\d+)_(\d+) will do it, if it is totally missing, (\d+)_(\d+) will be the regex, and finally, if the word must be in Caps : [A-Z]+_(\d+)_(\d+).

answered Sep 3, 2014 at 17:59

user3398633

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4 Comments

Jonathan Wood Over a year ago

I'll try that. What happens if the "SORT_" is missing in this case?

Felipe Oriani Over a year ago

He want a generic solution, to get the numbers in a string using regex.

Jonathan Wood Over a year ago

I want it to fail if "SORT" is missing, because that means something is not as expected.

user3398633 Over a year ago

@JonathanWood Then the first regex will do it, it won't match at all if this isn't SORT : proof

MethodMan · Accepted Answer · 2014-09-03 18:14:13Z

2

If you want an example using the Split() Function here is what you could do

var splitStr = "SORT_123_456";
var sortable = splitStr.Split('_');
if (sortable[0].Contains("SORT"))
{
    //do your sorting logic because you have a sortable 
    sortable[1] //will be "123"
    sortable[2] //will be "456"
}

or you could check for string.Empty

var splitStr = "SORT_123_456";
var sortable = splitStr.Split('_');
if (!sortable[0] == string.Empty)
{
    //do your sorting logic because you have a sortable 
    sortable[1] //will be "123"
    sortable[2] //will be "456"
}

answered Sep 3, 2014 at 18:14

MethodMan

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3 Comments

Jonathan Wood Over a year ago

In fact, this is what I ended up doing because it seemed simpler and may be more performant. I've marked Carlier Robin's post as the answer though, just because it more accurately answers what I originally asked.

MethodMan Over a year ago

totally understandable I was just providing you with a different approach hence the many ways to skin a cat as we say.. :)

Kuba Wyrostek Over a year ago

+1 I am totally in favor of substr/indexof solutions in trivial patterns such as this.

Nicholas Carey · Accepted Answer · 2014-09-03 18:55:00Z

1

This is the simple way. One simple regular expression. It validates the source string and extracts and captures all the the numeric fields, regardless of number of such fields found:

string src = @"SORT_123_456_789" ;
Regex  rx = new Regex( @"^SORT(_\d+)*$" ) ;
Match  match = rx.Match( src ) ;

if ( !match.Success ) throw new InvalidOperationException() ;

int[] values = null ;
if ( match.Success )
{
  values = match
          .Groups[1]
          .Captures
          .Cast<Capture>()
          .Select( c => int.Parse( c.Value.Substring(1) ) )
          .ToArray()
          ;
}

edited Sep 3, 2014 at 18:55

answered Sep 3, 2014 at 18:41

Nicholas Carey

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