Why does splitting eliminate part of the String in this c# code?

Question

I am parsing text and if I encounter a time, I want to split the string. Here is an example:

At 12:30AM I got up. At 11:30PM I went to bed.

My code :

string time = @"[0-9]{2}:[0-9]{2}(A|P)M";
string test = "At 12:30AM I got up. At 11:30PM I went to bed.";
string[] result = Regex.Split(test, time);

foreach(string element in result)
{
   Console.WriteLine(element);
}

What I need to get:

At 12:30AM
I got up. At 11:30PM
I went to bed.

What I get:

At
 A
  I got up. At
 P
  I went to bed.

All that is left of the times are either A or P.

Aditi · Accepted Answer · 2013-02-22 05:54:37Z

1

Change the regex to

([0-9]{2}:[0-9]{2}[AP]M)

Thhe brackets around (A|P) are defining it as the capture group. You need the the whole time string to be captured. So put the brackets around the whole thing.

edited Feb 22, 2013 at 5:54

answered Feb 22, 2013 at 5:47

Aditi

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4 Comments

user541686 Over a year ago

Doesn't [A|P] match A, |, and P?

Aditi Over a year ago

| is a special character. So it won't be matched unless it comes with an escape character.

Aditi Over a year ago

Ohhk.. New to regex... changed!

Jason Renaldo Over a year ago

Thanks guys, all the answers were very helpful.

ilomambo · Accepted Answer · 2013-02-22 05:46:37Z

1

Because the split function separator is not included in the results.
If you want it to remain as a split element enclose it in parenthesis

string time = @"([0-9]{2}:[0-9]{2}(A|P)M)";

By the way, that's the reason that the 'A' and 'P' were left, because they were enclosed in parenthesis.

answered Feb 22, 2013 at 5:46

ilomambo

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1 Comment

Joe Over a year ago

Indeed; you want to use [AP] or (?:A|P) if you don't want to capture A or P on their own.

RoadBump · Accepted Answer · 2013-02-28 07:46:39Z

0

Use capturing groups.

string regex=@".+?(?:\b\d{2}:\d{2}(?:AM|PM)|$)";
MatchCollection matches=Regex.Matches(input,regex);
foreach(var match in matches)
    Console.WriteLine(match.Groups[0]);

edited Feb 28, 2013 at 7:46

answered Feb 22, 2013 at 5:48

RoadBump

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4 Comments

Alan Moore Over a year ago

-1. You really should test your solutions before you post them. All those forward slashes in the regex should be backslashes, the MatchesCollection class name should be MatchCollection, and you should be calling the Matches method instead of Match. And when you've fixed all that, it still won't do what the OP wants.

RoadBump Over a year ago

You're right about the fixes, but the final thing WILL do what the asker wants, or at least what he wrote. He want to include the words before the pattern, as seen in his example.

Alan Moore Over a year ago

'Fraid not. You left the semicolon off the first line and you've got the arguments to Matches() reversed. That's why you should always test before posting, even if you're totally confident in the logic of your answer. But your regex still isn't right, as you can see here. Maybe you're thinking of this?

RoadBump Over a year ago

You're right, my mistake. Thanks for correcting me. The site looks pretty cool...

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