Regular Expressions Next Word?

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Hello I need a bit of help to understand if its possible to match a string with regular expression but only to show the middle or next word to the string?

for example the format looks like

"Today Date: Monday23," or "Today Date Monday 23,"

I can successfully find and display the words "Today Date" but the day following and number are unknown.

What would be the regular expression for showing the day and number which is between "Today Date" and the end of the string which is a ","

thank you in advance!

Posted 9-Sep-12 0:42am

Dale 2012

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Martijn Kok · Accepted Answer · 2012-09-09T01:37:00

Solution 1

You can use the following regular expression:

VB

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    Dim text As String = "Today Date: Monday23,"

    text = GetMatchingText(text) 'You can replace text with some other String like for instance TextBox1.Text
End Sub

Private Function GetMatchingText(stringValue As String) As String
    Dim pattern As String = "Today Date\:? ([A-Za-z]+ ?\d+),"
    Dim result As String = String.Empty

    If Regex.IsMatch(stringValue, pattern) Then
        'Example assumes you have only one result.
        result = Regex.Match(stringValue, pattern).Groups(1).Value
    End If

    Return result
End Function

Replace your orginal string value with the return value of the function GetMatchingText.

A small explanation:
* the semicolon is optional so you can detect it with \:? (the question mark indicates it is optional)
* with the parenthesis ([A-Za-z]+ ?\d+) defines a group and the results you want
* [A-Za-z]+ indicates characters A to Z in both upper and lower case. The + defines 1 or more matches
* the \d+ is one or more digital numbers

The results can be accessed using the Groups collection. Groups(0) results in the entire match. The result you want is in the first group.

Posted 9-Sep-12 1:37am

Martijn Kok

Updated 9-Sep-12 23:29pm

v2

Comments

Dale 2012 9-Sep-12 22:21pm

thank you for this explanation I have one other question to this. The date Monday 23 is not always constant and changes from time to time to what ever day and number of day relates to the string which is unknown. Will this display anything no matter if it changes?

Martijn Kok 10-Sep-12 1:12am

It will also detect every combination of 1 word and 1 numberic value

Dale 2012 9-Sep-12 22:31pm

also the regular expression returns the word Form1 for some reason and not the string I am searching for any ideas?

Martijn Kok 10-Sep-12 1:21am

I haven't enough information to know what is the bug. If the code is placed in a form called Form1, then it looks like the name of your form gets in the result. You'll need to debug your code. Place some breakpoints and try to find where the result changes into Form1.

Dale 2012 9-Sep-12 22:51pm

the format might also be like so...

Today Date: Monday-23-2012 or
Today Date: Monday.23-2012

thank you

Martijn Kok 10-Sep-12 1:15am

With regular expressions there are always to question you have to ask yourself:
1. What are the different variations of texts I have to search?
2. What should your result look like?

In this case. You want the output to be: Monday-23-2012 and Monday.23-2012 or just Monday 23?

Dale 2012 10-Sep-12 2:25am

thats my problem in general it could be any of those formats within the string. I am unsure of how to search and display only the day and number of day.

Martijn Kok 10-Sep-12 3:13am

You could have a look at this article. It explains regularexpressions: http://www.codeproject.com/Articles/9099/The-30-Minute-Regex-Tutorial

Regulare expressions can be complex and it's exact use depends on the text to search and your requirements. Studying it yourself might prove to be quite usefull in the future.

If you have any control over the way your 'Today Date: (...)' is formatted. I would say, that you might make sure that one is always the same format. But you probably haven't any influence on it.

The next question is: What does your result have to look like. Do you want a date value or do you want a text value containing: 'Monday 23', 'Monday23', 'Monday-23-2012', 'Monday.23-2012'.

If the latter is the case you could use the generic
Today Date\:? (.+),
(assuming you have a comma at the end of the line)

Dale 2012 10-Sep-12 5:16am

thank you for this..... It does indeed display the correct to speak of but it also displays the word todays date and does not stop after the first "," mark. it goes on and on. how can I replace the unwanted text with nothing so that only the day and number show?....

thank you for you patients

Martijn Kok 10-Sep-12 5:31am

Regex does have a Replace method, how ever in this case it won't work as you need. A work around is getting the value of a Group and replace the original string with the value of this group. I have changed the solution to show this.

Dale 2012 10-Sep-12 11:21am

Wow this is pretty cool I played around with the idea you have given me but the expression does not return anything unless I alter it like so....

detections were:\:?(.+?),

This will display detections were: Name,

with this expression where do i add the group 1?

I have tried it like this

"detections were:\:?(.+?),\1 but it does not return just the Name, has no change

thank you I am trying to understand and with each post its getting easier

Martijn Kok 10-Sep-12 11:42am

I'm getting a little lost myself now :) I can't fully get a picture of what you are trying to achieve.

Are you trying to do another search with the text dectections were: Or are you trying to report an output text with detections were: Monday 23?

Dale 2012 10-Sep-12 11:25am

in your variable text as string I cannot use something so exact because its not within my knowledge what the string will be... it will change each time

Martijn Kok 10-Sep-12 11:34am

I introduced the variable 'text' to show as an example, you should replace it with the string that contains your text or use the function directly on your string.

Dale 2012 10-Sep-12 20:00pm

I am parsing the string with the word "detection were:" to find the match in the string that follows monday 23 but I do not wish to display "detection were:" so that what im left with is just monday 23 or whatever follows it.

Dale 2012 10-Sep-12 20:15pm

I only wish to see monday 23 nothing else

Dale 2012 10-Sep-12 20:15pm

can i use two regex one to match and one to exclude certain text?

Dale 2012 10-Sep-12 20:20pm

I have come one step closer but with still some unwanted characters.

by using this string

(":\s\:?(.+?,)", RegexOptions.IgnoreCase)

what i get is this

:monday 23,

I need to get rid of the : and the ,

Dale 2012 11-Sep-12 1:56am

Your conclusion to my questions were on the money I have finally figured it out thank you once again for all your help it has been a bit confusing learning this type of thing but now that i have a much better understanding of regular expressions I am very happy to have that under my belt.

Martijn Kok 11-Sep-12 3:13am

Great you solved it and managed to use it.

Regular expressions are a powerful tool. If you search google for 'regular expressions .net' you'll find some very useful resources, that will help you use the power of regular expressions.

I'm glad I could help.

Regards,

Martijn