boolean.co.nz » PHP

Speeding up PHP FOR loops

Boolean — Wed, 11 Apr 2012 06:36:40 +0000

Refactoring some client code the other day I found a lot of inefficient logic. Whilst this example is written in PHP the concept is applicable in other programming languages.

Many people use for loops in the belief that they are faster than a foreach, and while this is often the case it can be slower and less flexible if you make some simple mistakes. Consider the following:

A slow FOR loop

$text=”thequickbrownfoxjumpsoverthelazydog”;
for($i=0; $i < strlen($text); $i++){ // Loop through the characters
echo ( substr($text,$i,1) == ‘o’ ) ? “Its an o” : “Not an o”; // Display true or false as relevant
}

A faster FOR loop

$text=”thequickbrownfoxjumpsoverthelazydog”;
$length = strlen($text); // obtain length of the string
for($i=0; $i < $length ; $i++){ // Loop through the characters
echo ( substr($text,$i,1) == ‘o’ ) ? “Its an o” : “Not an o”; // Display true or false as relevant
}

The second loop is faster because it does not evaluate the string length each time the loop runs strlen($text) as in the first example. Small differences like this can have a large effect on the speed of scripts especially if there are many loops or iterations.

08/02/2012 Emergency PHP Updates on server

Boolean — Tue, 07 Feb 2012 21:42:11 +0000

EMERGENCY PHP UPDATES

We will be applying a PHP update to the servers later this evening.

This will take the primary PHP install from v5.3.9 to v5.3.10 and will resolve a vulnerability that has been patched in the 5.3.10 release.

The vulnerability present in 5.3.9 allows for the possibility of remote code execution depending on how large numbers and arrays are used.

As this is a security issue we will be performing emergency maintenance between midnight and 3am (GMT).

There should be no interruption to service however, as the work is being done on components critical to PHP based sites, this period should be considered at risk.

The work will cause slightly higher than normal load on the servers and may involve a restart of the web server.

In the worst cast scenario (such as a failed compile) the installer will restore a backup of the current working configuration.

No module or configuration changes will be made to the PHP stack and scripts should notice no difference.

You can view the change log on the php.net site: http://php.net/ChangeLog-5.php

Obtain Facebook likes via PHP SDK

Boolean — Sun, 29 Jan 2012 03:11:36 +0000

In an update to this post here is another way to obtain the number of likes for a Facebook page.

I’ll assume that you’ve already registered a Facebook application, have downloaded the PHP SDK and have included for use in your code.

require(‘facebook.php’);

Setup an array with your Facebook applications credentials

$facebook = new Facebook(array(
‘appId’ => ’000000000′, // Put appID here
‘secret’ => ’0000c000c000c000c’, // Put your secret key here
));

Decide which page you wish to obtain the number of likes for

$getRequest = $facebook->api(‘/cocacola’); // Lets look at the Facebook page for the popular soft drink
echo $getRequests['likes'];

Obviously you can consume, contrast and display this information in more exciting ways than simply echoing it to the screen. Enjoy.

Use PHP to display Gravatar images

Boolean — Fri, 14 Oct 2011 03:34:25 +0000

All URLs on Gravatar are based on the use of the hashed value of an email address. According to their best practice you should:

Trim leading and trailing whitespace from an email address
Force all characters to lower-case
md5 hash the final string

Of course in PHP this is trivial as the following function shows:

function fetchGravatar() {
$fetchHash = md5(strtolower(trim(‘your_email.address.com’)));
$GravatarImage = ‘http://www.gravatar.com/avatar/’ . $fetchHash;
return $GravatarImage;
}

Profiles are also available if you require them.

PHP Host Settings Without phpinfo()

Boolean — Wed, 05 Oct 2011 09:36:05 +0000

Occasionally a webhost will block the very useful phpinfo() command making it difficult to understand any limitations of the server configuration. This script can display relevant information to help you understand what is happening behind the scenes.

$d_func = ini_get(“disable_functions”);
$up_max = ini_get(“upload_max_filesize”);
$up_max = str_replace(“M”,”",$up_max);
$up_max_size = “Megabytes”;
$post_max = ini_get(“post_max_size”);
$post_max = str_replace(“M”,”",$post_max);
$post_max_size = “Megabytes”;
$input_max = ini_get(“max_input_time”);
$mem_limit = ini_get(“memory_limit”);
$mem_limit = str_replace(“M”,”",$mem_limit);
$mem_limit_size = “Megabytes”;
$exec_time = ini_get(“max_execution_time”);
$safe_mode = ini_get(“safe_mode”);

if(!is_null($d_func) && $d_func !== “”){echo “Disabled Functions: \n $d_func”;}
if(!is_null($safe_mode) && $safe_mode !== “”){echo “Safe Mode is Active
”;}
if($up_max >= 1001){$up_max = $up_max / 1024; $up_max_size = “Gigabytes”;
if($up_max >= 10001){$up_max = $up_max / 1024; $up_max_size = “Terabytes”;}}
if($post_max >= 1001){$post_max = $post_max / 1024; $post_max_size = “Gigabytes”;
if($post_max >= 10001){$post_max = $post_max / 1024;$post_max_size = “Terabytes”;}}
if (min($input_max,60)){$input_max = $input_max /60;}
if (min($exec_time,60)){$exec_time = $exec_time /60;}
if($mem_limit >= 1001){$mem_limit = $mem_limit / 1024; $mem_limit_size = “Gigabytes”;}

echo “Maximum Upload Size = $up_max $up_max_size
”;
echo “Maximum Post Size = $post_max $post_max_size
”;
echo “Maximum Input Time = $input_max minute/s
”;
echo “Memory Limit = $mem_limit $mem_limit_size
”;
echo “Maximum Execution Time = $exec_time minute/s
”;
?>

PHP Modulo Operator For Alternating Rows

Boolean — Fri, 30 Sep 2011 22:24:50 +0000

Alternating row colours within a grid of data can make for a more pleasant viewing experience and has become a popular styling method in recent times. I was a little incredulous at some code I saw recently to determine alternating rows so without further introduction, meet the Modulo operator which is a quick and easy way to get up and running:

for($i=0;$i<10;$i++){
if($i % 2){
// This is an even row
}else{
// This is an odd row
}
}

I’m sure you will be able to apply this to your own css or styling within your loops.

Use cURL to obtain remote filesize

Boolean — Mon, 19 Sep 2011 11:00:46 +0000

Sometimes you might want to determine a remote file size prior to determining further action to take. This is a quick function that utilises cURL to retrieve the file size in bytes.

function remoteFilesize ($URL){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $URL);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$info = curl_exec($ch);
curl_close($ch);
$info = explode(‘Content-Length:’, $info);
$info = explode(“Connection”,$info[1]);
return $info[0];
}
?>

Usage is simple:

echo remoteFilesize(“test.com/file.html”);

Get Facebook Likes and Shares via Graph API

Boolean — Sun, 11 Sep 2011 01:46:44 +0000

Facebook Like and Share count can easily be obtained from the Facebook Graph API. This is an extremely quick way to look up the JSON response from Facebook so that you can further process it for your own requirements.

$URL =’https://graph.facebook.com/cocacola’;
$JSON = file_get_contents($URL);
$Output = json_decode($JSON);
$Likes = 0;
if($Output->likes){
$Likes = $Output->likes;
}

echo “Number of likes for CocaCola’s Facebook Page = “.$Likes.”
”;

$URL2 =’https://graph.facebook.com/http://www.coca-cola.com’;
$JSON2 = file_get_contents($URL2);
$Output2 = json_decode($JSON2);
$Shares = 0;
if($Output2->shares){
$Shares = $Output2->shares;
}

echo “Number of shares for coca-cola.com = “.$Shares;
?>

UPDATE 29/01/2012: I’ve written a slightly different method using the PHP SDK in this post here

Currency Conversion using Yahoo Finance API

Boolean — Sat, 10 Sep 2011 00:54:08 +0000

Just a quick and dirty PHP function to retrieve information from the Yahoo Finance API to perform a currency conversion

function ConvertCurrency($From,$To,$Amount){
$URL = ‘http://finance.yahoo.com/d/quotes.csv?e=.csv&f=sl1d1t1&s=’. $From . $To .’=X’;
$Handle = @fopen($URL, ‘r’);

if ($Handle) {
$Result = fgets($Handle, 4096);
fclose($Handle);
}
$allData = explode(‘,’,$Result);
$Value = $allData[1];

return $Value * $Amount;
}

Usage:

$Amount = ConvertCurrency(“NZD”,”USD”,25);

PHP Script Execution Timer Class

Boolean — Wed, 23 Mar 2011 06:45:21 +0000

Often for testing the efficieny of some PHP code we use script execution calculations such as the microtime function. What is infinitely more useful however is the ability to time the execution of all, some, or multiple sections of code or series of lines.
Unfortunately I cant remember the origins of this timer class – but this code allows you to stop, start, pause and resume timing of specific sections of your php code. Thank you, whoever you may be.

Download the class here

Available methods:

start() – start/resume the timer
stop() – stop/pause the timer
reset() – reset the timer
get([$format]) Which can defaults to Timer::SECONDS but can also be Timer::MILLISECONDS or Timer::MICROSECONDS

Usage example:

$timer1 = new Timer();
$timer2 = new Timer();

$timer1->start();
// do some code

// calculate the time it takes to run a function
$timer2->start();
functionX();
$timer2->stop();

$timer1->stop();

print $timer1->get();
print $timer2->get();