Ex.

if (strlen($foo) < 5) { echo "Foo is too short"; }

vs.

if (!isset($foo{5})) { echo "Foo is too short"; }

• Calling isset() happens to be faster then strlen() because unlike strlen(), isset() is a language construct and not a function meaning that it’s execution does not require function lookups and lowercase. This means you have virtually no overhead on top of the actual code that determines the string’s length.
• When incrementing or decrementing the value of the variable $i++ happens to be a tad slower then ++$i. This is something PHP specific and does not apply to other languages, so don’t go modifying your C or Java code thinking it’ll suddenly become faster, it won’t. ++$i happens to be faster in PHP because instead of 4 opcodes used for $i++ you only need 3. Post incrementation actually causes in the creation of a temporary var that is then incremented. While pre-incrementation increases the original value directly. This is one of the optimization that opcode optimized like Zend’s PHP optimizer. It is a still a good idea to keep in mind since not all opcode optimizers perform this optimization and there are plenty of ISPs and servers running without an opcode optimizer.
• Not everything has to be OOP, often it is too much overhead, each method and object call consumes a lot of memory.
• Do not implement every data structure as a class, arrays are useful, too
• Don’t split methods too much, think, which code you will really re-use
• You can always split the code of a method later, when needed
• Make use of the countless predefined functions
• If you have very time consuming functions in your code, consider writing them as C extensions
• Profile your code. A profiler shows you, which parts of your code consumes how many time. The Xdebug debugger already contains a profiler. Profiling shows you the bottlenecks in overview
• mod_gzip which is available as an Apache module compresses your data on the fly and can reduce the data to transfer up to 80%
• Excellent Article about optimizing php by John Lim

As Reihold Webber pointed to a post from John Lim (found this article copied without state the source here), then i investigate further and truly that is an excellent best practice tutorial for optimizing the php code performance, covered almost all aspects from low level webserver configuration, PHP configuration, coding styling, and performace comparisson as well.

Another good practice for better php performance as written in cluesheet.com are:

• Do use single quotes over double quotes.
• Do use switch over lots of if statements
• Do avoid testing loop conditionals with function tests every iteration eg. for($i=0;i<=count($x);$i++){…
• Do use foreach for looping collections/arrays. PHP4 items are byval, greater than PHP5 items are byref
• Do consider using the Singleton Method when creating complex PHP classes.
• Do use POST over GET for all values that will wind up in the database for TCP/IP packet performance reasons.
• Do use ctype_alnum,ctype_alpha and ctype_digit over regular expression to test form value types for performance reasons.
• Do use full file paths in production environment over basename/fileexists/open_basedir to avoid performance hits for the filesystem having to hunt through the file path. Once determined, serialize and/or cache path values in a $_SETTINGS array. $_SETTINGS["cwd"]=cwd(./);
• Do use require/include over require_once/include_once to ensure proper opcode caching.
• Do use tmpfile or tempnam for creating temp files/filenames
• Do use a proxy to access web services (XML or JSOM) on foreign domains using XMLHTTP to avoid cross-domain errors. eg. foo.com<–>XMLHTTP<–>bar.com
• Do use error_reporting (E_ALL); during debug.
• Do set Apache allowoverride to “none” to improve Apache performance in accessing files/directories.
• Do use a fast fileserver for serving static content (thttpd). static.mydomain.com, dynamic.mydomain.com
• Do serialize application settings like paths into an associative array and cache or serialize that array after first execution.
• Do use PHP output control buffering for page caching of heavilty accessed pages
• Do use PDO prepare over native db prepare for statements. mysql_attr_direct_query=>1
• Do NOT use SQL wildcard select. eg. SELECT *
• Do use database logic (queries, joins, views, procedures) over loopy PHP.
• Do use shortcut syntax for SQL insers if not using PDO parameters parameters. eg. INSERT INTO MYTABLE (FIELD1,FIELD2) VALUES ((“x”,”y”),(“p”,”q”));

Another Interesting articles about optimizing php performance:

• PHP & Mysql Cache Performance Comparison
• Accelerating PHP Applications Slide presentation International PHP Conference 2004
• Caching output in PHP

source

Our Extensible Markup Language Text
I’m using the same text as Jubba’s XML Parsing tutorials, except I might add some attributes to show you the extra power of Simple XML:

<?xml version="1.0"?>
<news>
 <story>
 <headline> Godzilla Attacks LA! </headline>
 <description>Equipped with a Japanese Mind-control device, the giant monster has attacked important harbours along the California coast. President to take action. </description>
 </story>
 <story>
 <headline> Bigfoot Spotted at M.I.T. Dining Area </headline>
 <description>The beast was seen ordering a Snapple in the dining area on Tuesday. In a related story, Kirupa Chinnathambi, an MIT engineering student has been reported missing. </description>
 </story>
 <story>
 <headline> London Angel Saves England </headline>
 <description>The "London Angel" known only as "Kit" has saved the U.K. yet again. Reports have stated that she destroyed every single Churchill bobble-head dog in the country. A great heartfilled thank you goes out to her. </description>
 </story>
 <story>
 <headline> Six-eyed Man to be Wed to an Eight-armed Woman </headline>
 <description>Uhhhmmm... No comment really... just a little creepy to see them together... </description>
 </story>
 <story>
 <headline> Ahmed's Birthday Extravaganza! </headline>
 <description>The gifted youngster's birthday party should be a blast. He is turning thirteen and has requested a large cake, ice cream, and a petting zoo complete with pony rides. </description>
 </story>
</news>

Our PHP Code
I know you’re expecting a couple hundred or so lines of advanced PHP with impossible to understand comments. You’re wrong, here’s the two lines you need to get a Simple XML object:

//Since we're already using PHP5, why don't we exploit their easy to use file_get_contents() command?
$xmlFileData = file_get_contents(“input.xml”);
//Here's our Simple XML parser!
$xmlData = new SimpleXMLElement($xmlFileData);
//And here's the output.
print_r($xmlData);

Execute that on your PHP server, and you get some meaningless gibberish like the following.

SimpleXMLElement Object (
 [story] => Array (
 [0] => SimpleXMLElement Object (
 [headline] => Godzilla Attacks LA!
 [description] => Equipped with a Japanese Mind-control device, the giant monster has attacked important harbours along the California coast. President to take action.
 )
 [1] => SimpleXMLElement Object (
 [headline] => Bigfoot Spotted at M.I.T. Dining Area
 [description] => The beast was seen ordering a Snapple in the dining area on Tuesday. In a related story, Kirupa Chinnathambi, an MIT engineering student has been reported missing.
 )
 [2] => SimpleXMLElement Object (
 [headline] => London Angel Saves England
 [description] => The "London Angel" known only as "Kit" has saved the U.K. yet again. Reports have stated that she destroyed every single Churchill bobble-head dog in the country. A great heartfilled thank you goes out to her.
 )
 [3] => SimpleXMLElement Object (
 [headline] => Six-eyed Man to be Wed to an Eight-armed Woman
 [description] => Uhhhmmm... No comment really... just a little creepy to see them together...
 )
 [4] => SimpleXMLElement Object (
 [headline] => Ahmed's Birthday Extravaganza!
 [description] => The gifted youngster's birthday party should be a blast. He is turning thirteen and has requested a large cake, ice cream, and a petting zoo complete with pony rides.
 )
 )
 )
)

To actually get data from that jumble of values, we can access it as an array with a class applied to it. Like so:

//Retrieving the headline from the first story
$xmlHeadline = $xmlData->story[0]->headline;
//Printing our first headline
print($xmlHeadline);

But what if you wanted the date of the story, but didn’t want to have to add another node to the story array? Just add an attribute. And Simple XML can also handle attributes! So our new XML looks like:

<?xml version="1.0"?>
<news>
 <story>
 <headline date=”January 19, 2005”> Godzilla Attacks LA! </headline>
 <description>Equipped with a Japanese Mind-control device, the giant monster has attacked important harbours along the California coast. President to take action. </description>
 </story>
 <story>
 <headline date=”February 14, 2006”> Bigfoot Spotted at M.I.T. Dining Area </headline>
 <description>The beast was seen ordering a Snapple in the dining area on Tuesday. In a related story, Kirupa Chinnathambi, an MIT engineering student has been reported missing. </description>
 </story>
 <story>
 <headline date=”May 27, 2006”> London Angel Saves England </headline>
 <description>The "London Angel" known only as "Kit" has saved the U.K. yet again. Reports have stated that she destroyed every single Churchill bobble-head dog in the country. A great heartfilled thank you goes out to her. </description>
 </story>
 <story>
 <headline date=”June 3, 2006”> Six-eyed Man to be Wed to an Eight-armed Woman </headline>
 <description>Uhhhmmm... No comment really... just a little creepy to see them together... </description>
 </story>
 <story>
 <headline date=”July 28, 2006”> Ahmed's Birthday Extravaganza! </headline>
 <description>The gifted youngster's birthday party should be a blast. He is turning thirteen and has requested a large cake, ice cream, and a petting zoo complete with pony rides. </description>
 </story>
</news>

So now we have all our news and their dates, but how do we show it to people? We can use a simple foreach loop to output everything to people.

//Outputing all of our XML to people
foreach($xmlData->story as $story) {
 print(“<h2>” . $story->headline . “</h2><br />”);
 print($story->description . “<br />_________________________<br />”);
 print($story->headline["date"] . “<br /><br />”);

}

Of course the output doesn’t look very pretty, but you could write some nice CSS or something to fix that! Remember, this only works in PHP5, so get PHP5, because it’s so much better than any other version of PHP!

You have to have cURL enabled.

Take a look:

oops , Finish

This technique can be used anyone without having any advanced PHP knowledge. This tutorial will teach you how to use this command.

Our tutorial is divided into two main sections:

• Server Requirements
• Code Implementation

Server Requirements

In order to run this command you will need to have PHP installed on your server. You can check this with your hosting service provider. Any modern version of PHP will be sufficient to execute this command. Other than that, there are no specific server requirements.

Code Implimentation

We are going to create a very simple example in which a HOME page includes a HEADER into it. This means that we are going to need two pages the HOME page and teh HEADER page.

We will start off with the header page. Using any web editing tool, simply create an HTML page with the following content:

Note that you do not need to create a proper HTML file with <html>, <header>, or <body> tags, simply because our header page will not be displayed by the browser by itself and instead it will be included as part of our HOME page.

Save this file as header.html.

It is now time to create our HOME page. Using any web editing tool, create an HTML page with the following code:

Our page does not have anything in it yet other than the page title tag. We are now going to add our #include command in the body of the page:

That should insert our header at the start of our body when our page is displayed on the server. If you want to have other content in your page you can simply insert it below that tag.

That should do it. You now have to save this file as home.php. You file MUST END WITH THE .PHP EXTENSION FOR THE SERVER TO PROCESS THE COMMAND. DO NOT FORGET THIS.

That should do it, you will not be able to test this command on your computer unless if you have a PHP server installed. The easiest way to try this is to upload it to your server. Simply upload both files to the same directory and then access home.php to see the content of your header.html file displayed in there along with your home page content!

function mysql2json($mysql_result,$name){
$json="{\n\"$name\": [\n";
$field_names = array();
$fields = mysql_num_fields($mysql_result);
for($x=0;$x< $fields;$x++){
$field_name = mysql_fetch_field($mysql_result, $x);
if($field_name){
$field_names[$x]=$field_name->name;
}
}
$rows = mysql_num_rows($mysql_result);
for($x=0;$x< $rows;$x++){
$row = mysql_fetch_array($mysql_result);
$json.="{\n";
for($y=0;$y<count($field_names);$y++) {
$json.="\"$field_names[$y]\" :    \"$row[$y]\"";
if($y==count($field_names)-1){
$json.="\n";
}
else{
$json.=",\n";
}
}
if($x==$rows-1){
$json.="\n}\n";
}
else{
$json.="\n},\n";
}
}
$json.="]\n};";
return($json);
}

The first parameter is the result of the query, without any parsing, just the output of mysql_query function, the second parameter is the name you want to give to your JSON object.

Returns a string with the JSON notation of the result.

Let’s start coding…


<?php
$kb=512;
echo "streaming $kb Kb...<!-";
flush();
$time = explode(" ",microtime());
$start = $time[0] + $time[1];
for($x=0;$x<$kb;$x++){
echo str_pad('', 1024, '.');
flush();
}
$time = explode(" ",microtime());
$finish = $time[0] + $time[1];
$deltat = $finish - $start;
echo "-> Test finished in $deltat seconds. Your speed is ". round($kb / $deltat, 3)."Kb/s";
?>


Done. Analysis and considerations:

2: Declaring how much Kb I want to transmit to accomplish the test. This value can also be passed in POST or GET. In my example it is declared.

3: I write I am downloading data, and open a comment tag. Everithing I am sending from now on will not be displayed. It’s not necessary, but prevents the browser to be fullfilled of chars.

4: Flush the chache

5-6: Saving actual timestamp

7-9: For $kb times I send 1024 chars (1Kb) and flush the cache

11-12: Saving actual timestamp

13: Calculating difference between start and finish timestamps

14: Closing comment tag and writing test result, calculated as Kb/time

Done… very easy isn’t it?

Considerations and exceptions

I wasn’t able to get reliable speed values with $kb under 512. I noticed the higher this number, the more reliable the result.

In some php configurations, those with output buffering to “On”, php executes before sending headers, cookies, and so on, and the time calculated in that way is the time of pure execution (excluding tranfers). Disabling output buffering, however, results are reliable.

You can try the script at this page.