O'Reilly Answers

Topics: python

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  How to remove duplicate lines with regular expressions

  

  By StevenLevithan

  There is a variety of software (including the Unix command-line utility uniq and Windows PowerShell cmdlet Get-Unique) that can help you remove duplicate lines in a file or ...

  30 October 2009 - 08:35 AM | 0 Comments
  Tags:

  • duplicates
  • regex
  • regular expression
  • .NET
  • java
  • javascript
  • PCRE
  • perl
  • python
  • ruby
  • php

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  Why use built-in types in Python?

  

  By juliesteele

  If you've used lower-level languages such as C or C++, you know that much of your work centers on implementing objects—also known as data structures—to represent the components in your applica...

  02 October 2009 - 09:07 AM | 0 Comments
  Tags:

  • Python
  • types
  • objects
  • C
  • C++

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  How to Match IPv4 Addresses with Regular Expressions

  

  By Jan Goyvaerts

  If you want to check whether a certain string represents a valid IPv4 address in 255.255.255.255 notation, try one of these examples from Regular Expressions Cookbook: Simple regex to check fo...

  30 September 2009 - 01:11 PM | 0 Comments
  Tags:

  • python
  • perl
  • javascript
  • java
  • address
  • IPv4
  • regex
  • ruby
  • .Net

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  How to validate traditional date formats with regular expressions

  

  By Jan Goyvaerts

  If you want to validate dates in the traditional formats mm/dd/yy, mm/dd/yyyy, dd/mm/yy, and dd/mm/yyyy, using a simple regex that simply checks whether the input looks ...

  18 September 2009 - 12:45 PM | 0 Comments
  Tags:

  • ruby
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  • PCRE
  • javascript
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  • .Net
  • dates
  • regex

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  How to create regular expression objects

  

  By Jan Goyvaerts

  If you want to instantiate a regular expression object or otherwise compile a regular expression so you can use it efficiently throughout your application, try one of t...

  18 September 2009 - 10:51 AM | 0 Comments
  Tags:

  • php
  • perl
  • javascript
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  • vb.net
  • c#
  • objects
  • regex
  • python
  • ruby

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  How to search line by line with a regular expression

  

  By Jan Goyvaerts

  Traditional grep tools apply your regular expression to one line of text at a time, and display the lines matched (or not matched) by the regular expression. If you hav...

  18 September 2009 - 10:22 AM | 0 Comments
  Tags:

  • python
  • perl
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  • c#
  • search
  • regex
  • php
  • ruby

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  How to replace all matches in a regular expression

  

  By Jan Goyvaerts

  If you want to replace all matches of the regular exp​ression before with the replacement text after, try one of the following examples:C#You can use the static call when you process on...

  18 September 2009 - 09:56 AM | 0 Comments
  Tags:

  • perl
  • php
  • java
  • javascript
  • vb.net
  • c#
  • regex
  • replace
  • python
  • ruby

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  How to find a match within another match in a regular expression

  

  By Jan Goyvaerts

  Suppose you have an HTML file in which various passages are marked as bold with <b> tags. You want to find all numbers marked as bold. If some bold text contains multiple numbers, you want to ma...

  17 September 2009 - 04:46 PM | 0 Comments
  Tags:

  • ruby
  • python
  • perl
  • php
  • javascript
  • java
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  • c#
  • regex

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  How to match whole words with a regular expression

  

  By Jan Goyvaerts

  Create a regex that matches cat in My cat is brown, but not in category or bobcat. Create another regex that matches cat in staccato, but not in any of the three previous subject str...

  16 September 2009 - 03:20 PM | 0 Comments
  Tags:

  • regex
  • .Net
  • java
  • javascript
  • PCRE
  • perl
  • python
  • ruby

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  How to match something at the Start and/or End of a line with a regular expression

  

  By Jan Goyvaerts

  Create four regular expressions. Match the word alpha, but only if it occurs at the very beginning of the subject text. Match the word omega, but only if it occurs at the very e...

  16 September 2009 - 02:18 PM | 0 Comments
  Tags:

  • python
  • perl
  • PCRE
  • javascript
  • java
  • .Net
  • regex
  • ruby

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