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初心者向けの 40 以上の PHP の役立つヒント ?パート1

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Jun 23, 2016 pm 02:37 PM

PHP 學習指南

http://www.binarytides.com/category/php-2/tutorial/

このシリーズでは、改善と最適化に使用できるいくつかの役立つヒントとテクニックを検討します。あなたのphpコード。これらの PHP のヒントは初心者向けであり、すでに mvc フレームワークなどを使用している人向けではないことに注意してください。

テクニック 1. 相対パスを使用せず、代わりに ROOT パスを定義します。

このような行を見るのはよくあることです :

require_once('http://www.cnblogs.com/lib/some_class.php');

このアプローチ多くの欠點があります:

最初に php のインクルードパスで指定されたディレクトリを検索し、次に現(xiàn)在のディレクトリから検索します。
非常に多くのディレクトリがチェックされます。

スクリプトが別のディレクトリにある別のスクリプトによってインクルードされる場合、そのベースディレクトリは、インクルードスクリプトのディレクトリに変更されます。

もう 1 つの問題は、スクリプトが cron から実行されている場合、その親ディレクトリが作業(yè)ディレクトリとしてない可能性があることです。

そのため、絶対パスを使用することをお勧めします:

define('ROOT' , '/var/www/project/');require_once(ROOT . 'http://www.cnblogs.com/lib/some_class.php');//rest of the code

これは絶対パスであり、常に一定になります。しかし、これをさらに改善することができます。 /var/www/project ディレクトリは変更される可能性があるので、毎回変更するのでしょうか?いいえ、代わりに __FILE__ のようなマジック定數(shù)を使用して移植性を高めます。詳しく見てみましょう:

//suppose your script is /var/www/project/index.php//Then __FILE__ will always have that full path.define('ROOT' , pathinfo(__FILE__, PATHINFO_DIRNAME));require_once(ROOT . 'http://www.cnblogs.com/lib/some_class.php');//rest of the code

したがって、プロジェクトをオンラインサーバーに移動するなど、別のディレクトリに移動した場合でも、同じコードは変更せずに実行されます。

2. require 、 include 、 require_once 、または include_once は使用しないでください。

スクリプトには、次のように、クラスライブラリ、ユーティリティやヘルパー関數(shù)のファイルなど、さまざまなファイルを上部に含めることができます:

require_once('lib/Database.php');require_once('lib/Mail.php');require_once('helpers/utitlity_functions.php');

これはかなり原始的です。コードはもっと柔軟にする必要があります。ヘルパー関數(shù)を作成して、より簡単に組み込みます。例を見てみましょう:

function load_class($class_name){    //path to the class file    $path = ROOT . '/lib/' . $class_name . '.php');    require_once( $path ); }load_class('Database');load_class('Mail');

何か違いはありますか?絶対です。これ以上の説明は必要ありません。
これを気に入ったら、これをさらに改善できます :

function load_class($class_name){    //path to the class file    $path = ROOT . '/lib/' . $class_name . '.php');        if(file_exists($path))    {        require_once( $path );     }}

これでできることはたくさんあります :

同じクラスファイルを複數(shù)のディレクトリで検索します。
変更コードをどこにも壊すことなく、クラスファイルを含むディレクトリを簡単に取得できます。
ヘルパー関數(shù)、HTML コンテンツなどを含むファイルをロードするには、同様の関數(shù)を使用します。

3. アプリケーションでデバッグ環(huán)境を維持します。

開発中、データベースクエリをエコーし??、変數(shù)をダンプします。問題を作成し、問題が解決したら、コメントするか削除します。しかし、すべてをそのままにして、長期的には役立つようにするのは良い考えです

開発マシンではこれを?qū)g行できます:

define('ENVIRONMENT' , 'development');if(! $db->query( $query ){    if(ENVIRONMENT == 'development')    {        echo "$query failed";    }    else    {        echo "Database error. Please contact administrator";    }    }

サーバーではこれを?qū)g行できます:

define('ENVIRONMENT' , 'production');if(! $db->query( $query ){    if(ENVIRONMENT == 'development')    {        echo "$query failed";    }    else    {        echo "Database error. Please contact administrator";    }    }

4. セッション経由でステータスメッセージを伝播します

ステータスメッセージタスクの実行後に生成されるメッセージです。

<?phpif($wrong_username || $wrong_password){    $msg = 'Invalid username or password';}?><html><body><?php echo $msg; ?><form>...</form></body></html>

そのようなコードは一般的です。変數(shù)を使用してステータスメッセージを表示するには制限があります。これらをリダイレクト経由で送信することはできません (GET 変數(shù)として次のスクリプトに伝播しない限り、これは非常に愚かです)。大規(guī)模なスクリプトでは、複數(shù)のメッセージなどが存在する可能性があります。

最良の方法は、(同じページ上にある場合でも) セッションを使用してメッセージを伝達することです。このためには、すべてのページに session_start が必要です。

function set_flash($msg){    $_SESSION['message'] = $msg;}function get_flash(){    $msg = $_SESSION['message'];    unset($_SESSION['message']);    return $msg;}

そしてスクリプト內(nèi):

<?phpif($wrong_username || $wrong_password){    set_flash('Invalid username or password');}?><html><body>Status is : <?php echo get_flash(); ?><form>...</form></body></html>

5. 関數(shù)を柔軟にする

function add_to_cart($item_id , $qty){    $_SESSION['cart'][$item_id] = $qty;}add_to_cart( 'IPHONE3' , 2 );

単一の項目を追加する場合は、上記の関數(shù)を使用します。複數(shù)のアイテムを追加する場合、別の関數(shù)を作成しますか?いいえ。さまざまな種類のパラメータを受け取れるように関數(shù)を柔軟にするだけです。詳しく見てみましょう:

function add_to_cart($item_id , $qty){    if(!is_array($item_id))    {        $_SESSION['cart'][$item_id] = $qty;    }    else    {        foreach($item_id as $i_id => $qty)        {            $_SESSION['cart'][$i_id] = $qty;        }    }}add_to_cart( 'IPHONE3' , 2 );add_to_cart( array('IPHONE3' => 2 , 'IPAD' => 5) );

これで、同じ関數(shù)が異なる種類の出力を受け入れることができるようになりました。上記の內(nèi)容を多くの場所に適用すると、コードの機敏性が高まります。

6. php の終了タグがスクリプトの最後にある場合は省略します。

なぜこのヒントが、php のヒントに関する非常に多くのブログ投稿から省略されているのか不思議です。

すごい

これで多くの問題が回避されます。例を見てみましょう:

クラスファイル super_class.php

<?phpecho "Hello";//Now dont close this tag

今度は、index.php

<?phpclass super_class{    function super_function()    {        //super code    }}?>//super extra character after the closing tag

そして、Headers selected are selected エラーが表示されます。なぜ？なぜなら、「スーパー余分な文字」がエコーされ、すべてのヘッダーがそれに伴って行われたからです。デバッグを開始します。非常に余分なスペースを見つけるのに何時間も無駄にする必要があるかもしれません。

したがって、終了タグを省略する習慣をつけましょう:

require_once('super_class.php');//echo an image or pdf , or set the cookies or session data

その方が良いです。

7. すべての出力を 1 か所に集め、一気に出力します。ブラウザ

これは出力バッファリングと呼ばれます。次のようにさまざまな関數(shù)からコンテンツをエコーし??てきたとします。

<?phpclass super_class{    function super_function()    {        //super code    }}//No closing tag

そのようにする代わりに、まずすべての出力を 1 か所に集めます。関數(shù)の変數(shù)內(nèi)に保存することも、ob_start と ob_end_clean を使用することもできます。これで、次のようになります

function print_header(){    echo "<div id='header'>Site Log and Login links</div>";}function print_footer(){    echo "<div id='footer'>Site was made by me</div>";}print_header();for($i = 0 ; $i < 100; $i++){    echo "I is : $i <br />';}print_footer();

それでは、なぜ出力バッファリングを行う必要があるのですか:

You can change the output just before sending it to browser if you need to. Think about doing some str_replaces , or may be preg_replaces or may be adding some extra html at the end like profiler/debugger output Its a bad idea to send output to browser and do php processing at the same time. Have you ever seen a website where there is a Fatal error in the sidebar or in a box in the middle of the screen. You know why that happens ? Because processing and output are being mixed. 8. Send correct mime types via header when outputting non-html content

Lets echo some xml.

$xml = '<?xml version="1.0" encoding="utf-8" standalone="yes"?>';$xml = "<response>  <code>0</code></response>";//Send xml dataecho $xml;

Works fine. But it needs some improvement.

$xml = '<?xml version="1.0" encoding="utf-8" standalone="yes"?>';$xml = "<response>  <code>0</code></response>";//Send xml dataheader("content-type: text/xml");echo $xml;

Note that header line. That line tells the browser that the content is xml content. So the browser can handle it correctly. Many javascript libraries also rely on header information.

Similarly for javascript , css , jpg image , png image :

Javascript

header("content-type: application/x-javascript");echo "var a = 10";

CSS

header("content-type: text/css");echo "#div id { background:#000; }";

9. Set the correct character encoding for a mysql connection

Ever faced a problem that unicode/utf-8 characters are stored in mysql table correctly , phpmyadmin also shows them correct , but when you fetch them and echo on your page they do not show up correctly. The secret is mysql connection collation.

$host = 'localhost';$username = 'root';$password = 'super_secret';//Attempt to connect to database$c = mysqli_connect($host , $username, $password);		//Check connection validityif (!$c) {	die ("Could not connect to the database host: <br />". mysqli_connect_error());}		//Set the character set of the connectionif(!mysqli_set_charset ( $c , 'UTF8' )){	die('mysqli_set_charset() failed');}

Once you connect to the database , its a good idea to set the connections characterset. This is a must when you are working with multiple languages in your application.

Otherwise what will happen ? You will see lots of boxes and ???????? in non english text.

10. Use htmlentities with the correct characterset option

Prior to php 5.4 the default character encoding used is ISO-8859-1 which cannot display characters like À â etc.

$value = htmlentities($this->value , ENT_QUOTES , 'UTF-8');

Php 5.4 onwards the default encoding will be UTF-8 which will solve most problems , but still better be aware about it if your application is multilingual.

11. Do not gzip output in your application , make apache do that

Thinking of using ob_gzhandler ? No dont do that. It doesnt make sense. Php is supposed to write your application. Dont worry about how to optimise data transfer between server and browser inside Php.

Use apache mod_gzip/mod_deflate to compress content via the .htaccess file.

12. Use json_encode when echoing javascript code from php

There are times when some javascript code is generated dynamically from php.

$images = array( 'myself.png' , 'friends.png' , 'colleagues.png');$js_code = '';foreach($images as $image){$js_code .= "'$image' ,";}$js_code = 'var images = [' . $js_code . ']; ';echo $js_code;//Output is var images = ['myself.png' ,'friends.png' ,'colleagues.png' ,];

Be smart. use json_encode :

$images = array( 'myself.png' , 'friends.png' , 'colleagues.png');$js_code = 'var images = ' . json_encode($images);echo $js_code;//Output is : var images = ["myself.png","friends.png","colleagues.png"]

Isn't that neat ?

13. Check if directory is writable before writing any files

Before writing or saving any file , make sure you check that the directory is writable or not , and flash an error message if it is not. This will save you a lot of "debugging" time. When you are working on a linux , permissions have to be dealt with and there would be many many permission issues when directories would not be writable , files would not be readable and so on.

Make sure that your application is as intelligent as possible and reports the most important information in the shortest time.

$contents = "All the content";$file_path = "/var/www/project/content.txt";file_put_contents($file_path , $contents);

That is totally correct. But has some indirect problems. The file_put_contents may fail for a number of reasons :

Parent directory does not exist Directory exists , but is not writable File locked for writing ?

So its better to make everything clear before writing out to a file.

$contents = "All the content";$dir = '/var/www/project';$file_path = $dir . "/content.txt";if(is_writable($dir)){    file_put_contents($file_path , $contents);}else{    die("Directory $dir is not writable, or does not exist. Please check");}

By doing this you get the accurate information that where is a file write failing and why

14. Change permission of files that your application creates

When working in linux environment , permission handling can waste a lot of your time. Hence whenever your php application creates some files do a chmod over them to ensure they are "accessible" outside. Otherwise for example the files may be created by "php" user and you are working as a different user and the system wont let you access or open the file , and then you have to struggle to get root privileges , change the permissions of the file and so on.

// Read and write for owner, read for everybody elsechmod("/somedir/somefile", 0644);// Everything for owner, read and execute for otherschmod("/somedir/somefile", 0755);

15. Don't check submit button value to check form submission

if($_POST['submit'] == 'Save'){    //Save the things}

The above is mostly correct , except when your application is multi-lingual. Then the 'Save' can be many different things. How would you compare then. So do not rely on the value of submit button. Instead use this :

if( $_SERVER['REQUEST_METHOD'] == 'POST' and isset($_POST['submit']) ){    //Save the things}

Now you are free from the value the submit button

16. Use static variables in function where they always have same value

//Delay for some timefunction delay(){    $sync_delay = get_option('sync_delay');    	    echo "<br />Delaying for $sync_delay seconds...";    sleep($sync_delay);    echo "Done <br />";}

Instead use static variables as :

//Delay for some timefunction delay(){    static $sync_delay = null;	    if($sync_delay == null)    {	$sync_delay = get_option('sync_delay');    }	    echo "<br />Delaying for $sync_delay seconds...";    sleep($sync_delay);    echo "Done <br />";}

17. Don't use the $_SESSION variable directly

Some simple examples are :

$_SESSION['username'] = $username;$username = $_SESSION['username'];

But this has a problem. If you are running multiple applications on the same domain , the session variables my conflict. 2 different applications may set the same key name in the session variable. Take for example , a frontend portal , and the backend management application , on the same domain.

Hence use application specific keys with wrapper functions :

define('APP_ID' , 'abc_corp_ecommerce');//Function to get a session variablefunction session_get($key){    $k = APP_ID . '.' . $key;       if(isset($_SESSION[$k]))    {        return $_SESSION[$k];    }        return false;}//Function set the session variablefunction session_set($key , $value){    $k = APP_ID . '.' . $key;    $_SESSION[$k] = $value;        return true;}

18. Wrap utility helper functions into a class

So you have a lot of utility functions in a file like :

function utility_a(){    //This function does a utility thing like string processing}function utility_b(){    //This function does nother utility thing like database processing}function utility_c(){    //This function is ...}

And you use the function throughout your application freely. You may want to wrap them into a class as static functions :

class Utility{    public static function utility_a()    {            }        public static function utility_b()    {            }    public static function utility_c()    {            }}//and call them as $a = Utility::utility_a();$b = Utility::utility_b();

One clear benefit you get here is if php has inbuilt functions with similar names , then names will not conflict.
Another perspective , though little advanced is that you can maintain multiple versions of the same class in the same application without any conflict. Its basically encapsulation , nothing else.

19. Bunch of silly tips Use echo instead of print Use str_replace instead of preg_replace , unless you need it absolutely Do not use short tags Use single quotes instead of double quotes for simple strings Always remember to do an exit after a header redirect Never put a function call in a for loop control line. isset is faster than strlen Format your code correctly and consistently Do not drop the brackets of loops or if-else blocks.
Do not code like this :

if($a == true) $a_count++;

Its absolutely a WASTE.

Write

if($a == true){    $a_count++;}

Dont try to make your code shorter by eating up syntax. Rather make your logic shorter.

Use a proper text editor which has code highlighting. Code highlighting helps to create lesser errors. 20. Process arrays quickly with array_map

Lets say you want to trim all elements of an array. Newbies do it like this :

foreach($arr as $c => $v){	$arr[$c] = trim($v);}

But it can more cleaner with array_map :

$arr = array_map('trim' , $arr);

This will apply trim on all elements of the array $arr. Another similar function is array_walk. Check out the
documentation on these to know more.

21. Validate data with php filters

Have you been using to regex to validate values like email , ip address etc. Yes everybody had been doing that. Now lets
try something different, called filters.

The php filter extension provides simple way to validate or check values as being a valid 'something'.

22. Force type checking

$amount = intval( $_GET['amount'] );$rate = (int) $_GET['rate'];

Its a good habit.

23. Write Php errors to file using set_error_handler()

set_error_handler() can be used to set a custom error handler. A good idea would be write some important errors in a file for logging purpose

24. Handle large arrays carefully

Large arrays or strings , if a variable is holding something very large in size then handle with care. Common mistake is to create a copy and then run out of memory and get a Fatal Error of Memory size exceeded :

$db_records_in_array_format; //This is a big array holding 1000 rows from a table each having 20 columns , every row is atleast 100 bytes , so total 1000 * 20 * 100 = 2MB$cc = $db_records_in_array_format; //2MB moresome_function($cc); //Another 2MB ?

The above thing is common when importing a csv file or exporting table to a csv file

Doing things like above can crashs scripts quite often due to memory limits. For small sized variables its not a problem , but must be avoided when handling large arrays.

Consider passing them by reference , or storing them in a class variable :

$a = get_large_array();pass_to_function(&$a);

by doing this the same variable (and not its copy) will be available to the function. Check documentation

class A{    function first()    {        $this->a = get_large_array();        $this->pass_to_function();    }    function pass_to_function()    {        //process $this->a    }}

unset them as soon as possible , so that memory is freed and rest of the script can relax.

Here is a simple demonstration of how assign by reference can save memory in some cases

<?phpini_set('display_errors' , true);error_reporting(E_ALL);$a = array();for($i = 0; $i < 100000 ; $i++){	$a[$i] = 'A'.$i;}echo 'Memory usage in MB : '. memory_get_usage() / 1000000 . '<br />';$b = $a;$b[0] = 'B';echo 'Memory usage in MB after 1st copy : '. memory_get_usage() / 1000000 . '<br />';$c = $a;$c[0] = 'B';echo 'Memory usage in MB after 2st copy : '. memory_get_usage() / 1000000 . '<br />';$d =& $a;$d[0] = 'B';echo 'Memory usage in MB after 3st copy (reference) : '. memory_get_usage() / 1000000 . '<br />';

The output on a typical php 5.4 machine is :

Memory usage in MB : 18.08208
Memory usage in MB after 1st copy : 27.930944
Memory usage in MB after 2st copy : 37.779808
Memory usage in MB after 3st copy (reference) : 37.779864

So it can be seen that in the 3rd copy which was by reference memory was saved. Otherwise in all plain copies memory is used up more and more.

25. Use a single database connection, throughout the script

Make sure that you use a single connection to your database throughout your script. Open a connection right in the beginning and use it till the end , and close it at the end. Do not open connections inside functions like this :

function add_to_cart(){    $db = new Database();    $db->query("INSERT INTO cart .....");}function empty_cart(){    $db = new Database();    $db->query("DELETE FROM cart .....");}

Having multiple connections is a bad idea and moreover they slow down the execution since every connection takes time to create and uses more memory.

Use the singleton pattern for special cases like database connection.

26. Avoid direct SQL query , abstract it

$query = "INSERT INTO users(name , email , address , phone) VALUES('$name' , '$email' , '$address' , '$phone')";$db->query($query); //call to mysqli_query()

The above is the simplest way way of writing sql queries and interacting with databases for operations like INSERT, UPDATE, DELETE etc. But it has few drawbacks like:

All values have to be escaped everytime manually Manually verify the sql syntax everytime. Wrong queries may go undetected for a long time (unless if else checking done everytime) Difficult to maintain large queries like that

Solution: ActiveRecord

It involves writing simple functions that abstract the generation of sql queries, hence avoid writing of direct sql queries.

A very simple example of an activerecord insert function can be like this :

function insert_record($table_name , $data){    foreach($data as $key => $value)    {	//mysqli_real_escape_string        $data[$key] = $db->mres($value);    }		    $fields = implode(',' , array_keys($data));    $values = "'" . implode("','" , array_values($data)) . "'";        //Final query	    $query = "INSERT INTO {$table}($fields) VALUES($values)";		    return $db->query($query);}//data to be inserted in database$data = array('name' => $name , 'email' => $email  , 'address' => $address , 'phone' => $phone);//perform the INSERT queryinsert_record('users' , $data);

The above example shows how to insert data in a database, without actually having to write INSERT statements. The function insert_record takes care of escaping data as well. A big advantage here is that since the data is being prepared as a php array, any syntax mistake is caught instantly (by the php interpreter ofcourse).

This function can be part of a database class, and callable like this $db->insert_record(). Similar functions can be written for update, select, delete as well. Should be a good practise.

27. Cache database generated content to static files

Pages that are generated by fetching content from the database like cms etc, can be cached. It means that once generated, a copy of it can be writted to file. Next time the same page is requested, then fetch it from the cache directory, dont query the database again.

Benefits :

Save php processing to generate the page , hence faster execution Lesser database queries means lesser load on mysql database 28. Store sessions in database

File based sessions have many limitation. Applications using file based sessions cannot scale to multiple servers, since files are stored on a single server. But database can be access from multiple servers hence the the problem is solved there. Also on shared hosting, the session files reside in the tmp directory, which is readable by other accounts. This can be a security issue.

Storing session in database makes many other things easier like:

Restrict concurrent logins from same username. Same username cannot log in from 2 different places at same time Check online status of users more accurately 29. Avoid using globals Use defines/constants Get value using a function Use Class and access via $this 30. Use base url in head tag

Quick example :

<head>    <base href="http://www.domain.com/store/"></head><body>    <img src="happy.jpg" /></body></html>

The base tag is like a 'ROOT' url for all relative urls in the html body. Its useful when static content files are organised into directories and subdirectories.

Lets take an example

www.domain.com/store/home.php
www.domain.com/store/products/ipad.php

In home.php the following can be written :

<a href="home.php">Home</a><a href="products/ipad.php">Ipad</a>

But in ipad.php the links have to be like this :

<a href="../home.php">Home</a><a href="ipad.php">Ipad</a>

This is because of different directories. For this multiple versions of the navigation html code has to be maintained. So the quick solution is base tag.

<a href="home.php">Home</a><a href="products/ipad.php">Ipad</a>

Now this particular code will work the same way in the home directory as well as the product directory. The base href value is used to form the full url for home.php and products/ipad.php

31. Manage error reporting

error_reporting is the function to use to set the necessary level of error reporting required.
On a development machine notices and strict messages may be disabled by doing.

ini_set('display_errors', 1);error_reporting(~E_NOTICE & ~E_STRICT);

On production , the display should be disabled.

ini_set('display_errors', 0);error_reporting(~E_WARNING & ~E_NOTICE & ~E_STRICT);

It is important to note that error_reporting should never be set to 0 on production machines. Atleast E_FATALs have to be known. Just switch off the display using the display_errors directive. If error_reporting is set to 0, errors wont be raised at all keeping all problems in the dark.

After the display is switched off, the errors should be logged to a file for later analysis. This can be done inside the script using init_set.

ini_set('log_errors' , '1');ini_set('error_log' , '/path/to/errors.txt');ini_set('display_errors' , 0);error_reporting(~E_WARNING & ~E_NOTICE & ~E_STRICT);

Note :

1. The path '/path/to/errors.txt' should be writable by the web server for errors to be logged there.

2. A separate error file is specified , otherwise all logs would go inside the apache/web server error log and get mixed up with other apache errors.

3. Also since it is being setup in the current application , the error log will contain the errors of only the current application (there may be other applications running on the webserver).

4. The path can be somewhere inside the directory of the current application as well , so that the system directories like /var/log dont have to searched.

5. Dont set error_reporting to 0. It will not log anything then.

Alternatively set_error_handler should be used to set a custom user written function as the error handler. That particular function, for example can log all errors to a file.

Set 'display_errors=On' in php.ini on development machine

On development machine its important to enable display_errors right in the php.ini (and not rely on ini_set)
This is because any compile time fatal errors will now allow ini_set to execute , hence no error display
and a blank WHITE page.

Similarly when they are On in php.ini , switching it off in a script that has fatal errors will not work.

Set 'display_errors=Off' in php.ini on production machine

Do not rely on init_set('display_errors' , 0); simply because it will not get executed if any compile time fatal errors come in the script , and errors will be displayed right away.

32. Be aware of platform architecture

The length of integers is different on 32 and 64 bit architectures. So functions like strtotime give different results.

On a 64 bit machine you can see such output.

$ php -aInteractive shellphp > echo strtotime("0000-00-00 00:00:00");-62170005200php > echo strtotime('1000-01-30');-30607739600php > echo strtotime('2100-01-30');4104930600

But on a 32 bit machine all of them would give bool(false). Check here for more.

What would happen if an integer is left shifted more than 32 bits ? the result would be different on different machines.

33. Dont rely on set_time_limit too much

If you are limiting the maximum run-time of a script , by doing this :

set_time_limit(30);//Rest of the code

It may not always work. Any execution that happens outside the script via system calls/os functions like socket operations, database operations etc. will not be under control of set_time_limit.

So if a database operation takes lot of time or "hangs" then the script will not stop. Dont be surprised then. Make better strategies to handle the run-time.

34. Make a portable function for executing shell commands

system , exec , passthru , shell_exec are the 4 functions that are available to execute system commands. Each has a slightly different behaviour. But the problem is that when you are working on shared hosting environments some of the functions are selectively disabled. Most newbie programmers tend to first find out which function is enabled and then use it.

A better solution :

/**	Method to execute a command in the terminal	Uses :	1. system	2. passthru	3. exec	4. shell_exec*/function terminal($command){	//system	if(function_exists('system'))	{		ob_start();		system($command , $return_var);		$output = ob_get_contents();		ob_end_clean();	}	//passthru	else if(function_exists('passthru'))	{		ob_start();		passthru($command , $return_var);		$output = ob_get_contents();		ob_end_clean();	}	//exec	else if(function_exists('exec'))	{		exec($command , $output , $return_var);		$output = implode("\n" , $output);	}	//shell_exec	else if(function_exists('shell_exec'))	{		$output = shell_exec($command) ;	}	else	{		$output = 'Command execution not possible on this system';		$return_var = 1;	}	return array('output' => $output , 'status' => $return_var);}terminal('ls');

The above function will execute the shell command using whichever function is available , keeping your code consistent.

35. Localize your application

Localise your php application. Format dates and numbers with commas and decimals. Show the time according to timezone of the user.

36. Use a profiler like xdebug if you need to

Profilers are used to generate reports that show the time is taken by different parts of the code to execute. When writing large application where lots of libraries and other resources are working to do a cetain task, speed might be an important aspect to optimise.

Use profilers to check how your code is performing in terms of speed. Check out xdebug and webgrind.

37. Use plenty of external libraries

An application often needs more than what can be coded with basic php. Like generating pdf files, processing images, sending emails, generating graphs and documents etc. And there are lots of libraries out there for doing these things quickly and easily.

Few popular libraries are :

mPDF - Generate pdf documents, by converting html to pdf beautifully. PHPExcel - Read and write Excel files PhpMailer - Send html emails with attachments easily pChart - Generate graphs in php 38. Have a look at phpbench for some micro-optimisation stats

If you really want to achieve optimisation at the level of microtime then check phpbench ... it has some benchmarks for various syntax variations that can create significant difference.

39. Use an MVC framework

Its time to start using an MVC (Model view controller) framework like codeigniter. MVC does not make your code object oriented rightaway. The first thing they do is separate the php code from html code.

Clean separation of php and html code. Good for team work, when designers and coders are working together. Functions and functionalities are organised in classes making maintenance easy. Inbuilt libraries for various needs like email, string processing, image processing, file uploads etc. Is a must when writing big applications Lots of tips, techniques, hacks are already implemented in the framework 40. Read the comments on the php documentation website

The php documentation website has entries for each function, class and their methods. All those individual pages have got lots of user comments below them that contain a whole lot of valuable information from the community.

They contain user feedback, expert advice and useful code snippets. So check them out.

41. Go to the IRC channel to ask

The irc channel #php is the best place online to ask about php related things. Although there are lots of blogs, forums out there and even more coming up everyday, still when a specific problem arises the solution might not be available there. Then irc is the place to ask. And its totally free!!

42. Read open source code

Reading other open source applications is always a good idea to improve own skills if you have not already. Things to learn are techniques, coding style, comment style, organisation and naming of files etc.

The first open source thing that I read was the codeigniter framework. Its easy to developers to use, as well as easy to look inside. Here are a few more

1. Codeigniter
2. WordPress
3. Joomla CMS

43. Linux で開発する

すでに Windows で開発している場合は、Linux を試してみるとよいでしょう。私のお気に入りはubuntuです。これは単なる意見ではありますが、それでも開発には Linux の方がはるかに優(yōu)れた環(huán)境であると強く感じています。

Php アプリケーションは主に Linux (LAMP) 環(huán)境にデプロイされます。したがって、同様の環(huán)境で開発することは、堅牢なアプリケーションをより速く作成するのに役立ちます。

ほとんどの開発ツールは、Ubuntu の synaptic パッケージマネージャーから非常に簡単にインストールできます。さらに、セットアップと実行に必要な設(shè)定はほとんどありません。そして最も素晴らしいのは、それらはすべて無料であるということです。

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