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Rob Allen:
Throw an exception when simplexml_load_string fails
September 09, 2014 @ 09:27:13

In a quick post to his site Rob Allen shares a class that he's created to handle and throw an exception any time that the load from a SimpleXML parsing fails.

I keep having to look up how to stop the warning that are emitted when simplexml_load_string & simplexml_load_file fail, so this time I've written the world's simplest little class to take care of it for me from now on.

His "Xml" class wraps around the SimpleXML functionality and checks to see if the resulting object is false. If it is, it uses some internal error handling to fetch the error message result and throws it as a "RuntimeException". This error string comes from a "getXMLErrorString" function that uses the libxml_get_errors function to get the resulting error list.

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simplexml load string file fail exception error handling

Link: http://akrabat.com/php/throw-an-exception-when-simplexml_load_string-fails/

SitePoint PHP Blog:
How to Create a Unique 64bit Integer from String
August 14, 2014 @ 12:55:33

In the latest post to the SitePoint PHP blog Vova Feldman shows you how to create an integer from a hash string that's both 64 bit and unique each time it's generated.

PHP provides the popular md5() hash function out of the box, which returns 32 a hex character string. It's a great way to generate a fingerprint for any arbitrary length string. But what if you need to generate an integer fingerprint out of a URL?

He describes the real-world situation he was facing - a rating widget that needed a randomized integer based on the page using it - and the two "sub-challenges" that make it up: url canonization and the string to unique 64 bit problem. He tackles each problem and shares code snippets showing the process and how it can be put to use. He also includes some interesting metrics at the end of the post showing the level of hash collisions (hint, it's a very low number).

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unique integer string 64bit tutorial md5 hash

Link: http://www.sitepoint.com/create-unique-64bit-integer-string/

Edd Mann:
Reversing a Unicode String in PHP using UTF-16BE/LE
May 12, 2014 @ 10:55:00

Edd Mann looks at an issue in his latest post that caused him problems in a recent project, reversing a Unicode string with UTF-16BE/LE.

Last week I was bit by the Unicode encoding issue when trying to naively manipulate a user's input using PHP's built-in string functions. PHP simply assumes that all characters are a single byte (octet) and the provided functions use this assumption when processing a string. [...] You should be aware that in 'Western Europe' we commonly only use the basic ASCII character-set (consisting of 7 bytes). This makes the transition to the popular 'UTF-8' Unicode representation almost seamless, as the two map one-to-one. I wish to however, discuss how to reverse a Unicode string (UTF-8) using a combination of endianness magic and the 'strrev' function.

He provides two different approaches to the problem. The first he calls the "naive" approach because it corrupts characters needing more than the two-byte representation. His second solution, the "endianness" method, converts the string to big-endian first (UTF-16) and then back to UTF-8 for more correct handling.

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unicode string utf8 utf16 bigendian endian convert reverse string

Link: http://eddmann.com/posts/reversing-a-unicode-string-in-php-using-utf-16-be-le

NetTuts.com:
Refactoring Legacy Code Part 2 - Magic Strings & Constants
April 03, 2014 @ 12:47:46

NetTuts.com has posted the second part of their "Refactoring Legacy Code" series today continuing on from their beginning of the series. They continue the refactor of their "trivia" application.

Old code. Ugly code. Complicated code. Spaghetti code. Jibberish nonsense. In two words, Legacy Code. This is a series that will help you work and deal with it. We first met our legacy source code in our previous lesson. [...] The time for the first changes have come and what better way to understand a difficult code base than start to extract magic constants and strings into variables? These seemingly simple tasks will give us greater and sometimes unexpected insights into the inner workings of legacy code. We will need to figure out the intentions of the original code author and find the proper names for the pieces of code that we've never seen before.

They talk about refactoring out things like "magic strings" and other hard-coded return values and checks. They mention updating the tests to reflect these changes while keeping an eye out for "magic constants" as well.

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refactoring unittest magic string constant trivia

Link: http://code.tutsplus.com/tutorials/refactoring-legacy-code-part-2-magic-strings-constants--cms-20527

Dougal Campbell:
mysql vs mysqli in WordPress
March 07, 2014 @ 10:59:52

In his latest post Dougal Campbell shares his findings from a bug he was having with a plugin in WordPress. It revolved around the use of mysql or mysqli and errors being thrown to his logs.

The plugin had previously worked fine (it generates a sidebar widget), and I wasn't actively working on my site, so I wasn't really sure when it had quit working. In the course of debugging the problem, I discovered that the plugin was throwing warnings in my PHP error log regarding the mysql_real_escape_string() function. As a quick fix, I simply replaced all of those calls with WordPress' esc_sql() function. Voila, problem fixed.

He was interested in why this worked, though, and went digging in the code. As it turns out, the WordPress code tries to determine which mysql extension you have support for. As it turns out, his installation fit the "mysqli profile" so the "mysql_real_escape_string" wasn't available. To the WordPress users out there, he suggests esc_sql or $wpdb->prepare() instead.

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mysql mysqli wordpress escape string extmysql

Link: http://dougal.gunters.org/blog/2014/03/06/mysql-vs-mysqli-wordpress

Simon Champion:
PHP Upgrade Broke My Data Importer
June 27, 2013 @ 12:13:45

In his latest post Simon Champion recounts some of the issues he had when upgrading to PHP 5.4, what's usually a smooth transition from PHP 5.3. His specific problem came in a difference between the previous mysql_query call and the more-correct PDO usage.

Our office is in the thoes of a large-scale upgrade of the servers in our data center. The new version of Debian (version 7, or "Wheezy") has been officially released, having been in beta for the last few millenia, and our Ops team are slowly installing it across all our servers. This is great news, as it means we get to upgrade to PHP 5.4. Woohoo! New shininess. [...] We were ready. The upgrade should have been a breeze. But it wasn't.

He talks about his process of digging through the code trying to figure out why a call to import a CSV file into MySQL was failing. Their Data Importer component started failing with an error from MySQL about the "LOAD INFILE" not being allowed for use. He shares a "work around" that's not ideal (using exec) that manually imports the file into the database. He does point out that it could be something Debian-specific as they don't upgrade the version, just apply security patches retroactively.

We're making an effort to stick to modern PHP coding standards, so we're using PDO throughout, which makes is all the more galling. [...] Given that we do have a work-around now and everything is back up and running, I'm going to have to let this one drop; I don't have the time to try chasing it any more. But I hope this blog post will prove useful to anyone else having the same issue.
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upgrade data importer mysql infile load pdo mysqlquery

Link: http://spudley.com/blog/php-upgrade-broke-my-data-importer

Bob Majdak:
On SQL in PHP
May 16, 2013 @ 10:11:29

In a new post to his site Bob Majdak looks at using SQL in PHP and some of the challenges he's come across (some of them with his own tools). He talks about things line inline SQL, loading SQL by unique key or creating a "build object".

There is no right or wrong way, but no matter what there is no *pretty* way to do SQL inside of a PHP application. I have been having a personal debate with myself all week about how to make SQL statements nicer in an application without going to a huge DBAL package like Doctrine.

He looks at each idea and provides some of the pros and cons about each of them, noting that he hasn't quite decided on which is the best method. Some sample code is included to help clarify the points, showing the "find by unique key" version and how a more complex query might be created with the "builder object."

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sql load unique key build object pros cons method inline

Link: http://catch404.net/2013/05/on-sql-in-php

Josh Adell:
Serializing Data Like a PHP Session
May 02, 2013 @ 09:11:33

In this new post Josh Adell looks at working with PHP sessions and how you can manually encode data to look as if it came from the normal session handling.

If you have ever popped open a PHP session file, or stored session data in a database, you may have noticed that this serialization looks very similar to the serialize function's output, but it is not the same. Recently, I needed to serialize data so that it looked like PHP session data (don't ask why; I highly suggest not doing this if it can be avoided.) It turns out, PHP has a function that encodes data in this format: session_encode.

Unfortunately, this method doesn't take arguments - it just outputs the encoded version of the current session data. So, he came up with his own encode/decode methods that use the PHP session, extract the serialized string and return it.

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serialize data session string unserialize

Link: http://blog.everymansoftware.com/2013/05/serializing-data-like-php-session.html

PHPMaster.com:
Parsing XML With SimpleXML
February 12, 2013 @ 12:48:34

On PHPMaster.com today there's a new tutorial introducing you to SimpleXML, a handy bit of functionality included with the base PHP install to make working with XML (well, reading it) much simpler.

Parsing XML essentially means navigating through an XML document and returning the relevant data. An increasing number of web services return data in JSON format, but a large number still return XML, so you need to master parsing XML if you really want to consume the full breadth of APIs available. Using PHP's SimpleXML extension that was introduced back in PHP 5.0, working with XML is very easy to do. In this article I'll show you how.

He starts with some basic usage of the SimpleXML parsing, giving an example XML to parse, the resulting object and how to access the data inside it. There's also a bit about dealing with namespaces in the XML you're parsing and a more practical example - parsing the output of a YouTube feed to get links to various videos.

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parse xml simplexml introduction tutorial


Sherif Ramadan:
How to Write an Operator Precedence Parser in PHP
January 21, 2013 @ 11:21:22

Sherif Ramadan has a post looking at creating a better operator precedence parser in PHP. His example is a fully PHP implementation that takes equation strings and evaluates them to create the result.

Operator precedence parsers are very simple on the surface. So don't feel in the least bit intimidated, because by the time you've read through this I hope to have you walk away with a solid foundation on how to write your very own operator precedence parser. The goal is to understand how to solve the problem of operator precedence parsing, and not necessarily to write your own parser. Learning how the problem can be solved is the most important thing to take away from this article.

He starts with an introduction to the concepts behind "operator precedence" including processing order and grouping. He also mentions infix and postfix (RPN) notations for handling different formats of equations. He used the "Shunting-yard Algorithm" and how it relates to handling the different parts of the equation, one at a time, in the correct order. He rest of the post is dedicated to the details of the execution in the tool, including code examples and the tokenization of the strings passed into it.

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operator precedence parser string token shuntingyard algorithm



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