regex - Have trouble understanding capturing groups and back references -

July 15, 2011

To know about any order regular expression, I decided to go through a book about them, Regular introduction . And I know that it is silly but I do not understand one of the introductory examples.

  (\ d) \ d \ 1

sample text:

  123-456-7890

(should be occupied by the first number, 123 )

Can anyone say what is happening here?

As far as I can understand, the first \ d occupies the number 123. For later use, the group backfruit (points) limits the brackets group's scope. But what else does \ d do?

Simple explanation, like a small child or a golden dog.

 matches string "123-456-7890" but this is  "323 " (which can be part of a larger string, for example " 323- first digit ("3") \ d: second digit ("2") \ 1: The first group (which was "3")    Now, if your book shows that  (\ d) \ d \ 1 \ / code> is passed to  "123"  should be Captured  "123-456-7890" , then there may be an error ...


















Get link





Facebook





X





Pinterest





Email





Other Apps




Comments





Post a Comment







Popular Posts




Xml parsing with python -



    I am using  xml  with Python  xmltodict . But I'm getting the following error,    xml.parsers.expat.ExpatError: mismatched tag: line 2890, column2    this is my code,    import xmltodict import urllib2 url = "url here" data = xmltodict.parse (urllib2.urlopen (url) .read () print data    I have tried to use the  Entry    here, with the at print, the print code 'urlib2 import lxml.etree',    Url = "Url here" xmldata = urllib2.urlopen (url) .read () root = ET.frost string (xmldata) print 'full' print route    This also helps me Error,    lxml.etree.XMLSyntaxError: Opening and closing tag mismatch: Client ID line 54 and type, line 55, column 14    I know that there is a problem in  XML   My question is, what is the way to read all the nodes except that it is  xml ?      






c# - WPF UserControl.Loaded event does not trigger -



    my program when I (mouseenter event) a TransportOrderLineDetailView to hover over a certain UserControl (Here I use TransportOrderLineUserControl) Should be shown.   The TransportOrderLineDetailView should be placed at the bottom right of my screen. For this I want to see the actual Wide & amp; The actual highlight for the actual placement is because those 2 properties require a different value than 0, because I execute this code with the DetailView.Loaded event.   I use the exact same type for two other items I do not work for TransportOrderLineDetailView   Code where the scene is generated:.    TransportOrderLineDetailView tolDetailView = new TransportOrderLineDetailView (New TransportOrderLineDetailViewModel (transportOrderLine)); Window.DetailContent = tolView; TolView.Loaded + = SetDetailViewOnUI;    code-behind view:    public TransportOrderLineDetailView (TransportOrderLineDetailViewModel detailViewModel) {InitializeComponent (); Datacontex = descriptionviewmodel; }    M...











ios - Pixel position of UIImageView in coordinate system -



    I am stuck in an interesting situation where I have 1.4, 1.4 x for reset, y is a pixel dot Start by putting imageview .. and why .. any document link?   Please any light please.   Thank you.       View = [[UIView alloc] initWithFrame: CGRectMake (10, 50, 20, 20)]; View.backgroundColor = [UIColor greenColor]; [Self.view addSubview: view]; Scene 2 = [[UIView alloc] initWithFrame: CGRectMake (10.4, 70, 20, 20)]; View2.backgroundColor = [UIColor redColor]; [Self.view addSubview: view2]; Scene 3 = [[UIView alloc] initWithFrame: CGRectMake (11, 90, 20, 20)]; View3.backgroundColor = [UIColor blue color]; [Self.view addSubview: view3];    The first is a visual reference, I know that its original x is at 20px.   Be careful here, due to retina @ 2x resolution 10 points x = 20 px, and 11 points x = 22 px. You speak in the code in the code, and give a pixel result on the screen.   I tried to change the X coordinate gradually here I found:     9.75 & lt; X & lt; = 10.25: Red square star...








Powered by Blogger

Six

Search This Blog

regex - Have trouble understanding capturing groups and back references -

Comments

Post a Comment