# PHP Style Guide All rules and guidelines in this document apply to PHP files unless otherwise noted. References to PHP/HTML files can be interpreted as files that primarily contain HTML, but use PHP for templating purposes. > The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC 2119](http://www.ietf.org/rfc/rfc2119.txt). Most sections are broken up into two parts: 1. Overview of all rules with a quick example 2. Each rule called out with examples of do's and don'ts **Icon Legend**: `·` Space, `⇥` Tab, `↵` Enter/Return ## Table of Contents 1. [**Files**](#1-files) 1. [File Format](#file-format) 2. [Filename](#filename) 2. [**Skeleton**](#2-skeleton) 3. [**PHP Tags**](#3-php-tags) 1. [Open Tag](#1-open-tag) 2. [Close Tag](#2-close-tag) 3. [Open/Close Tag](#3-openclose-tag) 4. [Short Open Tag](#4-short-open-tag) 5. [Short Echo Tag](#5-short-echo-tag) 4. [**End of File**](#4-end-of-file) 5. [**Namespaces**](#5-namespaces) 1. [Namespace Declaration](#1-namespace-declaration) 2. [Namespace Name](#2-namespace-name) 3. [Multiple Namespaces](#3-multiple-namespaces) 4. [Magic Constant](#4-magic-constant) 6. [**Comments**](#6-comments) 1. [Single-line Comments](#1-single-line-comments) 2. [Multi-line Comments](#2-multi-line-comments) 3. [Header Comments](#3-header-comments) 4. [Divider Comments](#4-divider-comments) 5. [Comments](#5-comments) 6. [Blocks of Code](#6-blocks-of-code) 7. [Ambiguous Numbers](#7-ambiguous-numbers) 8. [External Variables](#8-external-variables) 7. [**Includes**](#7-includes) 1. [Include/Require Once](#1-includerequire-once) 2. [Parenthesis](#2-parenthesis) 3. [Purpose of Include](#3-purpose-of-include) 8. [**Formatting**](#8-formatting) 1. [Line Length](#1-line-length) 2. [Line Indentation](#2-line-indentation) 3. [Blank Lines](#3-blank-lines) 4. [Text Alignment](#4-text-alignment) 5. [Trailing Whitespace](#5-trailing-whitespace) 6. [Keywords](#6-keywords) 7. [Variables](#7-variables) 8. [Global Variables](#8-global-variables) 9. [Constants](#9-constants) 10. [Statements](#10-statements) 11. [Operators](#11-operators) 12. [Unary Operators](#12-unary-operators) 13. [Concatenation Period](#13-concatenation-period) 14. [Single Quotes](#14-single-quotes) 15. [Double Quotes](#15-double-quotes) 9. [**Functions**](#9-functions) 1. [Function Name](#1-function-name) 2. [Function Prefix](#2-function-prefix) 3. [Function Call](#3-function-call) 4. [Function Arguments](#4-function-arguments) 5. [Function Declaration](#5-function-declaration) 6. [Function Return](#6-function-return) 10. [**Control Structures**](#10-control-structures) 1. [If, Elseif, Else](#1-if-elseif-else) 2. [Switch, Case](#2-switch-case) 3. [While, Do While](#3-while-do-while) 4. [For, Foreach](#4-for-foreach) 5. [Try, Catch](#5-try-catch) 11. [**Classes**](#11-classes) 1. [Class File](#1-class-file) 2. [Class Namespace](#2-class-namespace) 3. [Class Name](#3-class-name) 4. [Class Documentation](#4-class-documentation) 5. [Class Definition](#5-class-definition) 6. [Class Properties](#6-class-properties) 7. [Class Methods](#7-class-methods) 8. [Class Instance](#8-class-instance) 12. [**Best Practices**](#12-best-practices) 1. [Variable Initialization](#1-variable-initialization) 2. [Initialization/Declaration Order](#2-initializationdeclaration-order) 3. [Globals](#3-globals) 4. [Explicit Expressions](#4-explicit-expressions) 5. [E_STRICT Reporting](#5-e_strict-reporting) ## 1. Files This section describes the format and naming convention of PHP files. #### File Format 1. **Character encoding** MUST be set to UTF-8 without BOM * Sublime.app → `File` › `Save with Encoding` › `UTF-8` 2. **Line endings** MUST be set to Unix (LF) * Sublime.app → `View` › `Line Endings` › `Unix` #### Filename 1. **Letters** MUST be all lowercase * e.g. `autoloader.php` 2. **Words** MUST be separated with a hyphen * e.g. `app-config.php` ▲ [Table of Contents](#table-of-contents) ## 2. Skeleton This section showcases a barebones PHP file with its minimum requirements. Line by line breakdown: * **Line 1**: PHP open tag * **Line 2**: Blank line * **Line 3**: Your code * **Line 4**: Blank line * **Line 5**: End-of-file comment * **Line 6**: Blank line 
<?php

// your code

// EOF
▲ [Table of Contents](#table-of-contents) ## 3. PHP Tags This section describes the use of PHP tags in PHP and PHP/HTML files. 1. [**Open tag**](#1-open-tag) MUST be on its own line and MUST be followed by a blank line * i.e. `` 3. [**Open/close tag**](#3-openclose-tag) MUST be on one line in PHP/HTML files * i.e. `` 4. [**Short open tag**](#4-short-open-tag) MUST NOT be used * i.e. ` ### 1. Open Tag Open tag MUST be on its own line and MUST be followed by a blank line. #### ✖ Incorrect 
<?php print_welcome_message();
↳ Incorrect because ` <?php print_welcome_message(); ↳ Incorrect because ` <?php print_welcome_message(); ▲ [PHP Tags](#3-php-tags) ### 2. Close Tag Close tag MUST NOT be used in PHP files. #### ✖ Incorrect 
<?php

print_welcome_message();

?>
↳ Incorrect because `?>` was used. #### ✔ Correct 
<?php

print_welcome_message();
▲ [PHP Tags](#3-php-tags) ### 3. Open/Close Tag Open/close tag MUST be on one line in PHP/HTML files. #### ✖ Incorrect 
<div>
	<h1><?php
	print_welcome_message();
	?></h1>
</div>
↳ Incorrect because `` are not on one line. #### ✔ Correct 
<div>
	<h1><?php print_welcome_message(); ?></h1>
</div>
▲ [PHP Tags](#3-php-tags) ### 4. Short Open Tag Short open tag MUST NOT be used. #### ✖ Incorrect 
<?

print_welcome_message();
↳ Incorrect because ` <?php print_welcome_message(); ▲ [PHP Tags](#3-php-tags) ### 5. Short Echo Tag Short echo tag SHOULD be used in PHP/HTML files. #### ~ Acceptable 
<div>
	<p><?php echo get_welcome_message(); ?></p>
</div>
↳ Acceptable, but ` <div> <p><?= get_welcome_message(); ?></p> </div> ▲ [PHP Tags](#3-php-tags) ## 4. End of File This section describes how every PHP file must end. End-of-file comment: * MUST be included at the end of a file * i.e. `// EOF` * MUST be on its own line * i.e. `↵` `// EOF` * MUST be surrounded by blank lines * i.e. `...` `↵` `↵` `// EOF` `↵` #### ✖ Incorrect 
<?php

print_welcome_message();
↳ Incorrect because `// EOF` is missing. 
<?php

print_welcome_message(); // EOF
↳ Incorrect because `// EOF` is not on its own line. 
<?php

print_welcome_message();
// EOF
↳ Incorrect because `// EOF` is not surrounded by blank lines. #### ✔ Correct 
<?php

print_welcome_message();

// EOF
▲ [Table of Contents](#table-of-contents) ## 5. Namespaces This section describes how to use one or more namespaces and their naming convention. 1. [**Namespace declaration**](#1-namespace-declaration) MUST be the first statement and MUST be followed by a blank line * i.e. ` ### 1. Namespace Declaration Namespace declaration MUST be the first statement and MUST be followed by a blank line. #### ✖ Incorrect 
<?php

print_welcome_message();

namespace MyCompany;

// EOF
↳ Incorrect because `namespace MyCompany;` is not the first statement. 
<?php

namespace MyCompany;
print_welcome_message();

// EOF
↳ Incorrect because `namespace MyCompany;` is not followed by a blank line. #### ✔ Correct 
<?php

namespace MyCompany;

print_welcome_message();

// EOF
▲ [Namespaces](#5-namespaces) ### 2. Namespace Name Namespace name MUST start with a capital letter and MUST be camelcase. #### ✖ Incorrect 
<?php

namespace myCompany;

// EOF
↳ Incorrect because `myCompany` does not start with a capital letter. 
<?php

namespace MyCOMPANY;

// EOF
↳ Incorrect because `MyCOMPANY` is not written in camelcase. #### ✔ Correct 
<?php

namespace MyCompany;

// EOF
▲ [Namespaces](#5-namespaces) ### 3. Multiple Namespaces Multiple namespaces MUST use the curly brace syntax. #### ✖ Incorrect 
<?php

namespace MyCompany\Model;

namespace MyCompany\View;

// EOF
↳ Incorrect because there are two namespaces and the curly brace syntax was not used. #### ✔ Correct 
<?php

namespace MyCompany\Model {
	// model body
}

namespace MyCompany\View {
	// view body
}

// EOF
▲ [Namespaces](#5-namespaces) ### 4. Magic Constant Magic constant SHOULD be used to reference the namespace name. #### ~ Acceptable 
<?php

namespace MyCompany\Model {
	// model body
}

namespace MyCompany\View {
	$welcome_message = MyCompany\View\get_welcome_message();
}

// EOF
↳ Acceptable, but using `__NAMESPACE__` instead of `MyCompany\View` is preferred. #### ✔ Preferred 
<?php

namespace MyCompany\Model {
	// ModuleOne body
}

namespace MyCompany\View {
	$welcome_message = __NAMESPACE__ . '\\' . get_welcome_message();
}

// EOF
▲ [Namespaces](#5-namespaces) ## 6. Comments This section describes how comments should be formatted and used. 1. **[Single-line comments](#1-single-line-comments)** MUST use two forward slashes * e.g. `// My comment` 2. **[Multi-line comments](#2-multi-line-comments)** MUST use the block format * i.e. `/**` `↵` `* My comment` `↵` `*/` 3. **[Header comments](#3-header-comments)** SHOULD use the block format * i.e. `/**` `↵` `* Name of code section` `↵` `*/` 4. **[Divider comments](#4-divider-comments)** SHOULD use the block format with asterisks in between * i.e. `/**` `75 asterisks` `*/` 5. **[Comments](#5-comments)** MUST be on their own line * i.e. `↵` `// My comment` 6. **[Blocks of code](#6-blocks-of-code)** SHOULD be explained or summarized * e.g. `// Compare user accounts from export against expired accounts in system` 7. **[Ambiguous numbers](#7-ambiguous-numbers)** MUST be clarified * e.g. `// 1,000 processable records per hour API limit` 8. **[External variables](#8-external-variables)** MUST be clarified * e.g. `// Database object included in file.php` ▲ [Table of Contents](#table-of-contents) ### 1. Single-line Comments Single-line comments MUST use two forward slashes. #### ✖ Incorrect 
<?php

/* This is a comment */

// EOF
↳ Incorrect because it uses `/*` and `*/` for a single-line comment. #### ✔ Correct 
<?php

// This is a comment

// EOF
▲ [Comments](#6-comments) ### 2. Multi-line Comments Multi-line comments MUST use the block format. #### ✖ Incorrect 
<?php

// This is a
// multi-line
// comment

// EOF
↳ Incorrect because it uses `//` for a multi-line comment. #### ✔ Correct 
<?php

/**
 * This is a
 * multi-line
 * comment
 */

// EOF
▲ [Comments](#6-comments) ### 3. Header Comments Header comments SHOULD use the block format. 
<?php

/**
 * Global application settings
 */

define('SETTING_ONE', '');
define('SETTING_TWO', '');
define('SETTING_THREE', '');

// EOF
▲ [Comments](#6-comments) ### 4. Divider Comments Divider comments SHOULD use the block format with 75 asterisks in between. #### ✖ Incorrect 
<?php

/**#######################################################################*/

// EOF
↳ Incorrect because it uses `#` instead of `*`. 
<?php

/*************/

// EOF
↳ Incorrect because it uses 10 instead of 75 `*`. #### ✔ Correct 
<?php

/**
 * Beginning + Middle + End
 * 3 spaces + 75 spaces + 2 spaces = 80 character line limit
 */

/******************************************************************************/

// EOF
▲ [Comments](#6-comments) ### 5. Comments Comment MUST be on their own line. #### ✖ Incorrect 
<?php

print_welcome_message(); // Prints welcome message

// EOF
↳ Incorrect because `// Prints welcome message` is not on its own line. #### ✔ Correct 
<?php

// Prints welcome message
print_welcome_message();

// EOF
▲ [Comments](#6-comments) ### 6. Blocks of Code Blocks of code SHOULD be explained or summarized. #### ~ Acceptable 
<?php

foreach ($users as $user) {
	if ($expr1) {
		// ...
	} else {
		// ...
	}
	if ($expr2) {
		// ...
	} elseif ($expr3) {
		// ...
	} else {
		// ...
	}
	// ...
}

// EOF
↳ Acceptable, but block of code should be explained or summarized. #### ✔ Preferred 
<?php

/**
 * Get active website bloggers with profile photo for author page.
 * If no photo exists on website, check intranet.
 * If neither location has photo, send user email to upload one.
 */
foreach ($users as $user) {
	if ($expr1) {
		// ...
	} else {
		// ...
	}
	if ($expr2) {
		// ...
	} elseif ($expr3) {
		// ...
	} else {
		// ...
	}
	// ...
}

// EOF
▲ [Comments](#6-comments) ### 7. Ambiguous Numbers Ambiguous numbers MUST be clarified. #### ✖ Incorrect 
<?php

while ($expr && $x < 1000) {
	// ...
}

// EOF
↳ Incorrect because `1000` is not clarified. #### ✔ Correct 
<?php

// Script times out after 1,000 records
while ($expr && $x < 1000) {
	// ...
}

// EOF
▲ [Comments](#6-comments) ### 8. External Variables External variables MUST be clarified. #### ✖ Incorrect 
<?php

include_once 'some-file.php';

// ...

foreach($users as $user) {
	// ...
}

// EOF
↳ Incorrect because source of `$users` is not clear. #### ✔ Correct 
<?php

include_once 'some-file.php';

// ...

// $users from some-file.php
foreach($users as $user) {
	// ...
}

// EOF
▲ [Comments](#6-comments) ## 7. Includes This section describes the format for including and requiring files. 1. [**Include/require once**](#1-includerequire-once) SHOULD be used * i.e. `include` → `include_once`, `require` → `require_once` 2. [**Parenthesis**](#2-parenthesis) MUST NOT be used * e.g. `include_once('file.php');` → `include_once 'file.php';` 3. [**Purpose of include**](#3-purpose-of-include) MUST be documented with a comment * e.g. `// Provides WordPress environment` `↵` `require_once 'wp-load.php';` ▲ [Table of Contents](#table-of-contents) ### 1. Include/Require Once Include/require once SHOULD be used. #### ~ Acceptable 
<?php

include 'some-file.php';
require 'some-other-file.php';

// EOF
↳ Acceptable, but `_once` should be appended to `include` and `require` if possible. #### ✔ Preferred 
<?php

include_once 'some-file.php';
require_once 'some-other-file.php';

// EOF
▲ [Includes](#7-includes) ### 2. Parenthesis Parenthesis MUST NOT be used. #### ✖ Incorrect 
<?php

include_once('some-file.php');
require_once('some-other-file.php');

// EOF
↳ Incorrect because `include_once` and `require_once` are used with parenthesis. #### ✔ Correct 
<?php

include_once 'some-file.php';
require_once 'some-other-file.php';

// EOF
▲ [Includes](#7-includes) ### 3. Purpose of Include Purpose of include MUST be documented with a comment. #### ✖ Incorrect 
<?php

require_once 'some-file.php';

// EOF
↳ Incorrect because there is no comment as to what `some-file.php` does or provides. #### ✔ Correct 
<?php

// Provides XYZ framework
require_once 'some-file.php';

// EOF
▲ [Includes](#7-includes) ## 8. Formatting This section outline various, general formatting rules related to whitespace and text. 1. [**Line length**](#1-line-length) MUST NOT exceed 80 characters, unless it is text * i.e. `|---- 80+ chars ----|` → refactor expression and/or break list values 2. [**Line indentation**](#2-line-indentation) MUST be accomplished using tabs * i.e. `function func() {` `↵` `⇥` `...` `↵` `}` 3. [**Blank lines**](#3-blank-lines) SHOULD be added between logical blocks of code * i.e. `...` `↵` `↵` `...` 4. [**Text alignment**](#4-text-alignment) MUST be accomplished using spaces * i.e. `$var` `·` `·` `·` `= ...;` 5. [**Trailing whitespace**](#5-trailing-whitespace) MUST NOT be present after statements or serial comma break or on blank lines * i.e. no `...` `·` `·` `↵` `·` `↵` `...` 6. [**Keywords**](#6-keywords) MUST be all lowercase * e.g. `false`, `true`, `null`, etc. 7. [**Variables**](#7-variables) MUST be all lowercase and words MUST be separated by an underscore * e.g. `$welcome_message` 8. [**Global variables**](#8-global-variables) MUST be declared one variable per line and MUST be indented after the first * e.g. `global $var1,` `↵` `⇥` `$var2;` 9. [**Constants**](#9-constants) MUST be all uppercase and words MUST be separated by an underscore * e.g. `WELCOME_MESSAGE` 10. [**Statements**](#10-statements) MUST be placed on their own line and MUST end with a semicolon * e.g. `welcome_message();` 11. [**Operators**](#11-operators) MUST be surrounded by a space * e.g. `$total = 15 + 7;`, `$var .= '';` 12. [**Unary operators**](#12-unary-operators) MUST be attached to their variable or integer * e.g. `$index++`, `--$index` 13. [**Concatenation period**](#13-concatenation-period) MUST be surrounded by a space * e.g. `echo 'Read:' . $welcome_message;` 14. [**Single quotes**](#14-single-quotes) MUST be used * e.g. `echo 'Hello, World!';` 15. [**Double quotes**](#15-double-quotes) SHOULD NOT be used * e.g. `echo "Read: $welcome_message";` → `echo 'Read: ' . $welcome_message;` ▲ [Table of Contents](#table-of-contents) ### 1. Line Length Line length MUST NOT exceed 80 characters, unless it is text. #### ✖ Incorrect 
<?php

if(in_array('Slumdog Millionaire', $movies) && in_array('Silver Linings Playbook', $movies) && in_array('The Lives of Others', $movies) && in_array('The Shawshank Redemption', $movies)) {
	// if body
}

// EOF
↳ Incorrect because expression exceeds 80 characters and should be refactored. 
<?php

$my_movies = array('Slumdog Millionaire', 'Silver Linings Playbook', 'The Lives of Others', 'The Shawshank Redemption');

// EOF
↳ Incorrect because arguments exceed 80 characters and should be placed on their own line. #### ~ Acceptable 
<?php

$text = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec posuere rutrum tincidunt. Duis lacinia laoreet diam, nec consectetur magna facilisis eget. Quisque elit mauris, auctor quis vulputate id, sagittis nec tortor. Praesent fringilla lorem eu massa convallis ultricies. Maecenas lacinia porta purus, sollicitudin condimentum felis mollis a. Proin sed augue purus. Quisque scelerisque eros vitae egestas porta. Suspendisse vitae purus justo. Pellentesque justo nunc, luctus quis magna sit amet, venenatis rutrum ante. Nam eget nisi ultricies, sodales lectus vel, luctus dui. Cras pellentesque augue vitae nulla laoreet convallis. Mauris ut turpis mollis, elementum arcu eu, semper risus. Mauris vel urna ut felis blandit dictum. Aliquam sit amet tincidunt arcu. Nunc et elit quam. Aliquam hendrerit magna ut lacus semper consequat blandit eu ipsum.';

// EOF
↳ Acceptable because line length was exceeded due to text, not code. #### ✔ Correct 
<?php

$my_movies = array(
	'Slumdog Millionaire',
	'Silver Linings Playbook',
	'The Lives of Others',
	'The Shawshank Redemption'
);

$has_all_movies = true;

foreach($my_movies as $my_movie) {
	if(!in_array($my_movie, $movies)) {
		$has_all_movies = false;
	}
}

if($has_all_movies) {
	// if body
}

$some_long_variable = get_something_else(
	'from_some_other_function',
	'another_long_argument'
);

// EOF
▲ [Formatting](#8-formatting) ### 2. Line Indentation Line indentation MUST be accomplished using tabs. #### ✖ Incorrect 
<?php

function print_welcome_message() {
    echo WELCOME_MESSAGE;
}

// EOF
↳ Incorrect because spaces are used to indent `echo WELCOME_MESSAGE;` instead of a tab. #### ✔ Correct 
<?php

function print_welcome_message() {
	echo WELCOME_MESSAGE;
}

// EOF
▲ [Formatting](#8-formatting) ### 3. Blank Lines Blank lines SHOULD be added between logical blocks of code. #### ~ Acceptable 
<?php

$my_movies = array(
	'Slumdog Millionaire',
	'Silver Linings Playbook',
	'The Lives of Others',
	'The Shawshank Redemption'
);
$has_all_movies = true;
foreach($my_movies as $my_movie) {
	if(!in_array($my_movie, $movies)) {
		$has_all_movies = false;
	}
}
if($has_all_movies) {
	// if body
}

// EOF
↳ Acceptable, but can make scanning code more difficult. #### ✔ Preferred 
<?php

$my_movies = array(
	'Slumdog Millionaire',
	'Silver Linings Playbook',
	'The Lives of Others',
	'The Shawshank Redemption'
);

$has_all_movies = true;

foreach($my_movies as $my_movie) {
	if(!in_array($my_movie, $movies)) {
		$has_all_movies = false;
	}
}

if($has_all_movies) {
	// if body
}

// EOF
▲ [Formatting](#8-formatting) ### 4. Text Alignment Text alignment MUST be accomplished using spaces. #### ✖ Incorrect 
<?php

$movie_quotes = array(
	'slumdog_millionaire'		=> 'When somebody asks me a question, I tell them the answer.',
	'silver_linings_playbook'	=> 'I opened up to you, and you judged me.',
	'the_lives_of_others'		=> 'To think that people like you ruled a country.',
	'the_shawshank_redemption'	=> 'Get busy living, or get busy dying.'
);

// EOF
↳ Incorrect because tabs are used instead of spaces to vertically align `=>`. 
<?php

$movie_quotes = array(
    'slumdog_millionaire'       => 'When somebody asks me a question, I tell them the answer.',
    'silver_linings_playbook'   => 'I opened up to you, and you judged me.',
    'the_lives_of_others'       => 'To think that people like you ruled a country.',
    'the_shawshank_redemption'  => 'Get busy living, or get busy dying.'
);

// EOF
↳ Incorrect because spaces are used instead of tabs to indent array keys. #### ✔ Correct 
<?php

$movie_quotes = array(
	'slumdog_millionaire'       => 'When somebody asks me a question, I tell them the answer.',
	'silver_linings_playbook'   => 'I opened up to you, and you judged me.',
	'the_lives_of_others'       => 'To think that people like you ruled a country.',
	'the_shawshank_redemption'  => 'Get busy living, or get busy dying.'
);

// EOF
▲ [Formatting](#8-formatting) ### 5. Trailing Whitespace Trailing whitespace MUST NOT be present after statements or serial comma break or on blank lines. #### ✖ Incorrect 
<?php

$quotes_exist = false;  

print_welcome_message();

// EOF
↳ Incorrect because there are two spaces after `$quotes_exist = false;`. 
<?php

$my_movies = array(
	'Slumdog Millionaire', 
	'Silver Linings Playbook', 
	'The Lives of Others', 
	'The Shawshank Redemption'
);

// EOF
↳ Incorrect because there is a space after `,`. 
<?php

$quotes_exist = false;
  
print_welcome_message();

// EOF
↳ Incorrect because there are two spaces on the blank line below `$quotes_exist = false;`. #### ✔ Correct 
<?php

$quotes_exist = false;

print_welcome_message();

// EOF
 

<?php

$my_movies = array(
	'Slumdog Millionaire',
	'Silver Linings Playbook',
	'The Lives of Others',
	'The Shawshank Redemption'
);

// EOF
▲ [Formatting](#8-formatting) ### 6. Keywords Keywords MUST be all lowercase. #### ✖ Incorrect 
<?php

$is_true = FALSE;
$is_false = TRUE:
$movie_quote = NULL;

// EOF
↳ Incorrect because `FALSE`, `TRUE` and `NULL` are not all lowercase. #### ✔ Correct 
<?php

$is_true = false;
$is_false = true:
$movie_quote = null;

// EOF
▲ [Formatting](#8-formatting) ### 7. Variables Variables MUST be all lowercase and words MUST be separated by an underscore. #### ✖ Incorrect 
<?php

$welcome_Message = '';
$Welcome_Message = '';
$WELCOME_MESSAGE = '';

// EOF
↳ Incorrect because `$welcome_Message`, `$Welcome_Message` and `$WELCOME_MESSAGE` are not all lowercase. 
<?php

$welcomemessage = '';

// EOF
↳ Incorrect because `welcome` and `message` are not separated with an underscore. #### ✔ Correct 
<?php

$welcome_message = '';

// EOF
▲ [Formatting](#8-formatting) ### 8. Global Variables Global variables MUST be declared one variable per line and MUST be indented after the first. #### ✖ Incorrect 
<?php

global $app_config, $cache, $db_connection;

// EOF
↳ Incorrect because `$app_config`, `$cache` and `$db_connection` are together on one line. 
<?php

global $app_config,
$cache,
$db_connection;

// EOF
↳ Incorrect because `$db_connection` and `$cache` are not indentend once. #### ✔ Correct 
<?php

global $app_config,
	$cache,
	$db_connection;

// EOF
▲ [Formatting](#8-formatting) ### 9. Constants Constants MUST be all uppercase and words MUST be separated by an underscore. #### ✖ Incorrect 
<?php

define('welcome_Message', '');
define('Welcome_Message', '');
define('welcome_message', '');

// EOF
↳ Incorrect because `welcome_Message`, `Welcome_Message` and `welcome_message` are not all uppercase. 
<?php

define('WELCOMEMESSAGE', '');

// EOF
↳ Incorrect because `WELCOME` and `MESSAGE` are not separated with an underscore. #### ✔ Correct 
<?php

define('WELCOME_MESSAGE', '');

// EOF
▲ [Formatting](#8-formatting) ### 10. Statements Statements MUST be placed on their own line and MUST end with a semicolon. #### ✖ Incorrect 
<?php

$quotes_exist = false; print_welcome_message();

// EOF
↳ Incorrect because `$quotes_exist = false;` and `print_welcome_message();` are on one line. 
<div>
	<h1><?= print_welcome_message() ?></h1>
</div>
↳ Incorrect because `print_welcome_message()` is missing a semicolon. #### ✔ Correct 
<?php

$quotes_exist = false;
print_welcome_message();

// EOF
 

<div>
	<h1><?= print_welcome_message() ?></h1>
</div>
▲ [Formatting](#8-formatting) ### 11. Operators Operators MUST be surrounded a space. #### ✖ Incorrect 
<?php

$total=3+14;
$string='Hello, World! ';
$string.='Today is a good day!';

// EOF
↳ Incorrect because there is no space surrounding the `=`, `+` or `.=` sign. #### ✔ Correct 
<?php

$total = 3 + 14;
$string = 'Hello, World! ';
$string .= 'Today is a good day!';

// EOF
▲ [Formatting](#8-formatting) ### 12. Unary Operators Unary operators MUST be attached to their variable or integer. #### ✖ Incorrect 
<?php

$index ++;
-- $index;

// EOF
↳ Incorrect because there is a space before `++` and after `--`. #### ✔ Correct 
<?php

$index++;
--$index;

// EOF
▲ [Formatting](#8-formatting) ### 13. Concatenation Period Concatenation period MUST be surrounded by a space. #### ✖ Incorrect 
<?php

echo 'Hello, World! Today is '.$date.'!';

// EOF
↳ Incorrect because there is no space surrounding `.`. #### ✔ Correct 
<?php

echo 'Hello, World! Today is ' . $date . '!';

// EOF
▲ [Formatting](#8-formatting) ### 14. Single Quotes Single quotes MUST be used. #### ✖ Incorrect 
<?php

echo "Hello, World!";

// EOF
↳ Incorrect because `"Hello, World!"` is not written with single quotes. #### ✔ Correct 
<?php

echo 'Hello, World!';

// EOF
▲ [Formatting](#8-formatting) ### 15. Double Quotes Double quotes SHOULD NOT be used. #### ~ Acceptable 
<?php

echo "Hello, World! Today is $date!";

// EOF
↳ Acceptable, but burries the `$date` variable, which is why single quotes are preferred. 
<?php

echo "Hello, World! He's watching movies and she's reading books.";

// EOF
↳ Acceptable when long pieces of text have apostrophies that would need to be escaped. #### ✔ Preferred 
<?php

echo 'Hello, World! Today is ' . $date . '!';

echo 'Hello, World! He\'s watching movies and she\'s reading books.';

// EOF
▲ [Formatting](#8-formatting) ## 9. Functions This section describes the format for function names, calls, arguments and declarations. 1. [**Function name**](#1-function-name) MUST be all lowercase and words MUST be separated by an underscore * e.g. `function welcome_message() {` 2. [**Function prefix**](#2-function-prefix) MUST start with verb * e.g. `get_`, `add_`, `update_`, `delete_`, `convert_`, etc. 3. [**Function call**](#3-function-call) MUST NOT have a space between function name and open parenthesis * e.g. `func();` 4. [**Function arguments**](#4-function-arguments) * MUST NOT have a space before the comma * MUST have a space after the comma * MAY use line breaks for long arguments * MUST then place each argument on its own line * MUST then indent each argument once * MUST be ordered from required to optional first * MUST be ordered from high to low importance second * MUST use descriptive defaults * MUST use type hinting * e.g. `func($arg1, $arg2 = 'asc', $arg3 = 100);` 5. [**Function declaration**](#5-function-declaration) MUST be documented using [phpDocumentor](http://phpdoc.org/docs/latest/index.html) tag style and SHOULD include * Short description * Optional long description, if needed * @access: `private` or `protected` (assumed `public`) * @author: Author name * @global: Global variables function uses, if applicable * @param: Parameters with data type, variable name, and description * @return: Return data type, if applicable 6. [**Function return**](#6-function-return) * MUST occur as early as possible * MUST be initialized prior at top * MUST be preceded by blank line, except inside control statement * i.e. `if (!$expr) { return false; }` ▲ [Table of Contents](#table-of-contents) ### 1. Function Name Function name MUST be all lowercase and words MUST be separated by an underscore. #### ✖ Incorrect 
<?php

get_Welcome_Message();
Get_Welcome_Message();
GET_WELCOME_MESSAGE();

// EOF
↳ Incorrect because the function names are not all lowercase. 
<?php

getwelcomemessage();

// EOF
↳ Incorrect because `get`, `welcome` and `message` are not separated with an underscore. #### ✔ Correct 
<?php

get_welcome_message();

// EOF
▲ [Functions](#9-functions) ### 2. Function Prefix Function prefix MUST start with verb. #### ✖ Incorrect 
<?php

active_users();
network_location($location1, $location2);
widget_form($id);

// EOF
↳ Incorrect because functions are not prefixed with a verb. #### ✔ Correct 
<?php

get_active_users();
move_network_location($location1, $location2);
delete_widget_form($id);

// EOF
▲ [Functions](#9-functions) ### 3. Function Call Function call MUST NOT have a space between function name and open parenthesis. #### ✖ Incorrect 
<?php

print_welcome_message ();

// EOF
↳ Incorrect because there is a space between `get_welcome_message` and `()`. #### ✔ Correct 
<?php

print_welcome_message();

// EOF
▲ [Functions](#9-functions) ### 4. Function Arguments Function arguments: * MUST NOT have a space before the comma * MUST have a space after the comma * MAY use line breaks for long arguments * MUST then place each argument on its own line * MUST then indent each argument once * MUST be ordered from required to optional first * MUST be ordered from high to low importance second * MUST use descriptive defaults * MUST use type hinting #### ✖ Incorrect 
<?php

my_function($arg1 , $arg2 , $arg3);

// EOF
↳ Incorrect because there is a space before `,`. 
<?php

my_function($arg1,$arg2,$arg3);

// EOF
↳ Incorrect because there is no space after `,`. 
<?php

my_other_function($arg1_with_a_really_long_name,
	$arg2_also_has_a_long_name,
	$arg3
);

// EOF
↳ Incorrect because `$arg1_with_a_really_long_name` is not on its own line. 
<?php

my_other_function(
$arg1_with_a_really_long_name,
$arg2_also_has_a_long_name,
$arg3
);

// EOF
↳ Incorrect because arguments are not indented once. 
<?php

function get_objects($type, $order = 'asc', $limit) {
	// ...
}

// EOF
↳ Incorrect because `$type`, `$order` and `$limit` are not in order of required to optional. 
<?php

function get_objects($limit, $order, $type) {
	// ...
}

// EOF
↳ Incorrect because `$limit`, `$order` and `$type` are not in order of importance. 
<?php

function get_objects($type, $order = true, $limit = 100) {
	// ...
}

// EOF
↳ Incorrect because `true` is not a descriptive default for `$order`. 
<?php

function add_users_to_office($users, $office) {
	// ...
}

// EOF
↳ Incorrect because `$users` and `$office` are missing their data type. #### ✔ Correct 
<?php

my_function($arg1, $arg2, $arg3);

my_other_function(
	$arg1_with_a_really_long_name,
	$arg2_also_has_a_long_name,
	$arg3
);

function get_objects($type, $order = 'asc', $limit = 100) {
	// ...
}

function add_users_to_office(array $users, Office $office) {
	// ...
}

// EOF
▲ [Functions](#9-functions) ### 5. Function Declaration Function declaration MUST be documented using [phpDocumentor](http://phpdoc.org/docs/latest/index.html) tag style and SHOULD include: * Short description * Optional long description, if needed * @access: `private` or `protected` (assumed `public`) * @author: Author name * @global: Global variables function uses, if applicable * @param: Parameters with data type, variable name, and description * @return: Return data type, if applicable #### ✖ Incorrect 
<?php

function my_function($id, $type, $width, $height) {
	// ...
	return $Photo;
}

// EOF
↳ Incorrect because `my_function` is not documented. #### ✔ Correct 
<?php

/**
 * Get photo from blog author
 * 
 * Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut id volutpat 
 * orci. Etiam pharetra eget turpis non ultrices. Pellentesque vitae risus 
 * sagittis, vehicula massa eget, tincidunt ligula.
 *
 * @access private
 * @author Firstname Lastname
 * @global object $post
 * @param int $id Author ID
 * @param string $type Type of photo
 * @param int $width Photo width in px
 * @param int $height Photo height in px
 * @return object Photo
 */
function my_function($id, $type, $width, $height) {
	// ...
	return $Photo;
}

// EOF
▲ [Functions](#9-functions) ### 6. Function Return Function return: * MUST occur as early as possible * MUST be initialized prior at top * MUST be preceded by blank line, except inside control statement #### ✖ Incorrect 
<?php

function get_object() {
	$var = false;
	if($expr1) {
		// ...
		if($expr2) {
			// ...
		}
	}

	return $var;
}

// EOF
↳ Incorrect because `get_object` does not return as early as possible. 
<?php

function get_movies() {
	// ...

	return $movies;
}

// EOF
↳ Incorrect because `$movies` is not initialized at top. 
<?php

function get_movies() {
	$movies = array();
	// ...
	return $movies;
}

// EOF
↳ Incorrect because `return $movies` is not preceded by blank line. #### ✔ Correct 
<?php

function get_object() {
	$var = false;
	if (!$expr1) {
		return $var;
	}
	if (!$expr2) {
		return $var;
	}
	// ...

	return $var;
}

// EOF
 

<?php

function get_movies() {
	$movies = array();
	// ...

	return $movies;
}

// EOF
▲ [Functions](#9-functions) ## 10. Control Structures This section defines the layout and usage of control structures. Note that this section is separated into rules that are applicable to all structures, followed by specific rules for individual structures. * **Keyword** MUST be followed by a space * e.g. `if (`, `switch (`, `do {`, `for (` * **Opening parenthesis** MUST NOT be followed by a space * e.g. `($expr`, `($i` * **Closing parenthesis** MUST NOT be preceded by a space * e.g. `$expr)`, `$i++)`, `$value)` * **Opening brace** MUST be preceded by a space and MUST be followed by a new line * e.g. `$expr) {`, `$i++) {` * **Structure body** MUST be indented once and MUST be enclosed with curly braces (no shorthand) * e.g. `if ($expr) {` `↵` `⇥` `...` `↵` `}` * **Closing brace** MUST start on the next line * i.e. `...` `↵` `}` * **Nesting** MUST NOT exceed three levels * e.g. no `if ($expr1) { if ($expr2) { if ($expr3) { if ($expr4) { ` `...` `}}}}` In addition to the rules above, some control structures have additional requirements: 1. [**If, Elseif, Else**](#1-if-elseif-else) * `elseif` MUST be used instead of `else if` * `elseif` and `else` MUST be between `}` and `{` on one line 2. [**Switch, Case**](#2-switch-case) * Case statement MUST be indented once * i.e. `⇥` `case 1:` * Case body MUST be indented twice * i.e. `⇥` `⇥` `func();` * Break keyword MUST be indented twice * i.e. `⇥` `⇥` `break;` * Case logic MUST be separated by one blank line * i.e. `case 1: ... break;` `↵` `↵` `case 2: ... break;` 3. [**While, Do While**](#3-while-do-while) 4. [**For, Foreach**](#4-for-foreach) 5. [**Try, Catch**](#5-try-catch) * `catch` MUST be between `}` and `{` on one line ▲ [Table of Contents](#table-of-contents) ### 1. If, Elseif, Else * `elseif` MUST be used instead of `else if` * `elseif` and `else` MUST be between `}` and `{` on one line #### ✖ Incorrect 
<?php

if ($expr1) {
	// if body
} else if ($expr2) {
	// elseif body
} else {
	// else body
}

// EOF
↳ Incorrect because `else if` was used instead of `elseif`. 
<?php

if ($expr1) {
	// if body
}
elseif ($expr2) {
	// elseif body
}
else {
	// else body
}

// EOF
↳ Incorrect because `elseif` and `else` are not between `}` and `{` on one line. 
<?php

$result1 = if ($expr1) ? true : false;

if($expr2)
	$result2 = true;

// EOF
↳ Incorrect because structure body is not wrapped in curly braces. #### ✔ Correct 
<?php

if ($expr1) {
	// if body
} elseif ($expr2) {
	// elseif body
} else {
	// else body
}

if ($expr1) {
	$result1 = true;
} else {
	$result1 = false;
}

if ($expr2) {
	$result2 = true;
}

// EOF
▲ [Control Structures](#10-control-structures) ### 2. Switch, Case * Case statement MUST be indented once * Case body MUST be indented twice * Break keyword MUST be indented twice * Case logic MUST be separated by one blank line #### ✖ Incorrect 
<?php

switch ($expr) {
case 0:
	echo 'First case, with a break';
	break;

case 1:
	echo 'Second case, which falls through';
	// no break
case 2:
case 3:
case 4:
	echo 'Third case, return instead of break';
	return;

default:
	echo 'Default case';
	break;
}

// EOF
↳ Incorrect because `case 0` thru `default` are not indented once. 
<?php

switch ($expr) {
	case 0:
	echo 'First case, with a break';
	break;

	case 1:
	echo 'Second case, which falls through';
	// no break
	case 2:
	case 3:
	case 4:
	echo 'Third case, return instead of break';
	return;

	default:
	echo 'Default case';
	break;
}

// EOF
↳ Incorrect because `echo`, `break` and `return` are not indented twice. 
<?php

switch ($expr) {
	case 0:
		echo 'First case, with a break';
		break;
	case 1:
		echo 'Second case, which falls through';
		// no break
	case 2:
	case 3:
	case 4:
		echo 'Third case, return instead of break';
		return;
	default:
		echo 'Default case';
		break;
}

// EOF
↳ Incorrect because `case 0`, `case 1` thru `case 4`, and `default` are not separated by one blank line. #### ✔ Correct 
<?php

switch ($expr) {
	case 0:
		echo 'First case, with a break';
		break;

	case 1:
		echo 'Second case, which falls through';
		// no break
	case 2:
	case 3:
	case 4:
		echo 'Third case, return instead of break';
		return;

	default:
		echo 'Default case';
		break;
}

// EOF
▲ [Control Structures](#10-control-structures) ### 3. While, Do While #### ✔ Correct 
<?php

while ($expr) {
	// structure body
}

do {
	// structure body;
} while ($expr);

// EOF
▲ [Control Structures](#10-control-structures) ### 4. For, Foreach #### ✔ Correct 
<?php

for ($i = 0; $i < 10; $i++) {
	// for body
}

foreach ($iterable as $key => $value) {
	// foreach body
}

// EOF
▲ [Control Structures](#10-control-structures) ### 5. Try, Catch #### ✖ Incorrect 
<?php

try {
	// try body
}
catch (FirstExceptionType $e) {
	// catch body
}
catch (OtherExceptionType $e) {
	// catch body
}

// EOF
↳ Incorrect because `catch` is not between `}` and `{` on one line. #### ✔ Correct 
<?php

try {
	// try body
} catch (FirstExceptionType $e) {
	// catch body
} catch (OtherExceptionType $e) {
	// catch body
}

// EOF
▲ [Control Structures](#10-control-structures) ## 11. Classes This section describes class files, names, definitions, properties, methods and instantiation. 1. [**Class file**](#1-class-file) MUST only contain one definition and MUST be prefixed with `class-` * i.e. `class User` → `class-user.php`, `class Office` → `class-office.php` 2. [**Class namespace**](#2-class-namespace) MUST be defined and MUST include vendor name * e.g. `namespace MyCompany\Model;`, `namespace MyCompany\View;`, `namespace MyCompany\Controller;` 3. [**Class name**](#3-class-name) MUST start with a capital letter and MUST be camelcase * e.g. `MyCompany` 4. [**Class documentation**](#4-class-documentation) MUST be present and MUST use [phpDocumentor](http://phpdoc.org/docs/latest/index.html) tag style * i.e. `@author`, `@global`, `@package` 5. [**Class definition**](#5-class-definition) MUST place curly braces on their own line * i.e. `class User` `↵` `{` `↵` `...` `↵` `}` 6. [**Class properties**](#6-class-properties) * MUST follow [variable standards](#7-variables) * MUST specify visibility * MUST NOT be prefixed with an underscore if private or protected * e.g. `$var1;`, `private $var2;`, `protected $var3;` 7. [**Class methods**](#7-class-methods) * MUST follow [function standards](#9-functions) * MUST specify visibility * MUST NOT be prefixed with an underscore if private or protected * e.g. `func1()`, `private func2()`, `protected func3()` 8. [**Class instance**](#8-class-instance) * MUST start with capital letter * MUST be camelcase * MUST include parenthesis * e.g. `$user = new User();`, `$OfficeProgram = new OfficeProgram();` ▲ [Table of Contents](#table-of-contents) ### 1. Class File Class file MUST only contain one definition and MUST be prefixed with `class-`. #### ✖ Incorrect Filename: `class-user.php` 
<?php

namespace MyCompany\Model;

class User
{
	// ...
}

class Office
{
	// ...
}

// EOF
↳ Incorrect because `User` and `Office` are defined in one file. Filename: `user.php` 
<?php

namespace MyCompany\Model;

class User
{
	// ...
}

// EOF
↳ Incorrect because filename is not prefixed with `class-`. #### ✔ Correct Filename: `class-user.php` 
<?php

namespace MyCompany\Model;

class User
{
	// ...
}

// EOF
Filename: `class-office.php` 
<?php

namespace MyCompany\Model;

class Office
{
	// ...
}

// EOF
▲ [Classes](#11-classes) ### 2. Class Namespace Class namespace MUST be defined and MUST include vendor name. #### ✖ Incorrect 
<?php

class User
{
	// ...
}

// EOF
↳ Incorrect because there is no namespace defined. 
<?php

namespace Model;

class User
{
	// ...
}

// EOF
↳ Incorrect because vendor name is missing in the namespace name. #### ✔ Correct 
<?php

namespace MyCompany\Model;

class User
{
	// ...
}

// EOF
▲ [Classes](#11-classes) ### 3. Class Name Class name MUST start with a capital letter and MUST be camelcase. #### ✖ Incorrect 
<?php

namespace MyCompany\Model;

class officeProgram
{
	// ...
}

// EOF
↳ Incorrect because `officeProgram` does not start with a capital letter. 
<?php

namespace MyCompany\Model;

class Officeprogram
{
	// ...
}

// EOF
↳ Incorrect because `Officeprogram` is not camelcase. #### ✔ Correct 
<?php

namespace MyCompany\Model;

class OfficeProgram
{
	// ...
}

// EOF
▲ [Classes](#11-classes) ### 4. Class Documentation Class documentation MUST be present and MUST use [phpDocumentor](http://phpdoc.org/docs/latest/index.html) tag style. #### ✖ Incorrect 
<?php

namespace MyCompany\Model;

class User
{
	// ...
}

// EOF
↳ Incorrect because `User` is missing documentation. 
<?php

namespace MyCompany\View;

/**
 * User View
 */
class User
{
	// ...
}

// EOF
↳ Incorrect because `User` is missing [phpDocumentor](http://phpdoc.org/docs/latest/index.html) tags. #### ✔ Correct 
<?php

namespace MyCompany\View;

/**
 * User View
 *
 * @author Firstname Lastname
 * @global object $post
 * @package MyCompany\API
 */
class User
{
	// ...
}

// EOF
▲ [Classes](#11-classes) ### 5. Class Definition Class definition MUST place curly braces on their own line. #### ✖ Incorrect 
<?php

namespace MyCompany\Model;

class User {
	// ...
}

// EOF
↳ Incorrect because `{` is not on its own line. #### ✔ Correct 
<?php

namespace MyCompany\Model;

class User
{
	// ...
}

// EOF
▲ [Classes](#11-classes) ### 6. Class Properties Class properties: * MUST follow [variable standards](#7-variables) * MUST specify visibility * MUST NOT be prefixed with an underscore if private or protected #### ✖ Incorrect 
<?php

namespace MyCompany\Model;

class User
{
	// Public
	$var1;

	// Protected
	$var2;

	// Private
	$var3;
}

// EOF
↳ Incorrect because visibility is not specified for `$var1`, `$var2` and `$var3`. 
<?php

namespace MyCompany\Model;

class User
{
	public $var1;
	protected $_var2;
	private $_var3;
}

// EOF
↳ Incorrect because `protected` and `private` properties are prefixed with `_`. #### ✔ Correct 
<?php

namespace MyCompany\Model;

class User
{
	public $var1;
	protected $var2;
	private $var3;
}

// EOF
▲ [Classes](#11-classes) ### 7. Class Methods Class methods: * MUST follow [function standards](#9-functions) * MUST specify visibility * MUST NOT be prefixed with an underscore if private or protected #### ✖ Incorrect 
<?php

namespace MyCompany\Model;

class User
{
	// ...

	// Public
	function get_var1() {
		return $this->var1;
	}

	// Protected
	function get_var2() {
		return $this->var2;
	}

	// Private
	function get_var3() {
		return $this->var3;
	}
}

// EOF
↳ Incorrect because visibility is not specified for `get_var1()`, `get_var2()` and `get_var3()`. 
<?php

namespace MyCompany\Model;

class User
{
	// ...

	public function get_var1() {
		return $this->var1;
	}

	protected function _get_var2() {
		return $this->var2;
	}

	private function _get_var3() {
		return $this->var3;
	}
}

// EOF
↳ Incorrect because `protected` and `private` methods are prefixed with `_`. #### ✔ Correct 
<?php

namespace MyCompany\Model;

class User
{
	// ...

	public function get_var1() {
		return $this->var1;
	}

	protected function get_var2() {
		return $this->var2;
	}

	private function get_var3() {
		return $this->var3;
	}
}

// EOF
▲ [Classes](#11-classes) ### 8. Class Instance Class instance: * MUST follow [variable standards](#7-variables) * MUST include parenthesis #### ✖ Incorrect 
<?php

$office_program = new OfficeProgram;

// EOF
↳ Incorrect because `new OfficeProgram` is missing parenthesis. #### ✔ Correct 
<?php

$office_program = new OfficeProgram();

// EOF
▲ [Classes](#11-classes) ## 12. Best Practices 1. [**Variable initialization**](#1-variable-initialization) SHOULD occur prior to use and SHOULD occur early * e.g. `$var1 = '';`, `$var2 = 0;` 2. [**Initialization/declaration order**](#2-initializationdeclaration-order) * MUST lead with globals, follow with constants, conclude with local variables * MUST lead with properties and follow with methods in classes * MUST lead with `public`, follow with `protected`, conclude with `private` methods in classes * SHOULD be alphabetical within their type * i.e. `global $var1;`, `define('VAR2', '');`, `$var3 = 0;` 3. [**Globals**](#4-globals) SHOULD NOT be used * i.e. no `global $var;` 4. [**Explicit expressions**](#5-explicit-expressions) SHOULD be used * e.g. `if ($expr === false)`, `while ($expr !== true)` 5. [**E_STRICT reporting**](#6-e_strict-reporting) MUST NOT trigger errors * i.e. do not use deprecated functions, etc. ▲ [Table of Contents](#table-of-contents) ### 1. Variable Initialization Variable initialization SHOULD occur prior to use and SHOULD occur early. #### ~ Acceptable 
<?php

$movies = get_movies();

// EOF
↳ Acceptable, but `$movies` should be initialized prior to use. 
<?php

if ($expr) {
	// ....
}

$movies = array();
$movies = get_movies();

// EOF
↳ Acceptable, but `$movies` should be initialized earlier. #### ✔ Preferred 
<?php

$movies = array();

if ($expr) {
	// ....
}

$movies = get_movies();

// EOF
▲ [Best Practices](#12-best-practices) ### 2. Initialization/Declaration Order Initialization/declaration order: * MUST lead with globals, follow with constants, conclude with local variables * MUST lead with properties and follow with methods in classes * MUST lead with `public`, follow with `protected`, conclude with `private` methods in classes * SHOULD be alphabetical within their type #### ✖ Incorrect 
<?php

define('ENVIRONMENT', 'PRODUCTION');

$id = 0;

global $app_config;

// EOF
↳ Incorrect because `$app_config` is not first, `ENVIRONMENT` not second, and `$id` not third. 
<?php

namespace MyCompany\Model;

class Office
{
	public function get_name() {
		// ...
	}

	private $name;
}

// EOF
↳ Incorrect because `get_name()` is declared before `$name`. 
<?php

namespace MyCompany\Model;

class Office
{
	private $id;
	private $name;
	private $status;

	private function get_name() {
		// ...
	}

	public function get_id() {
		// ...
	}

	protected function get_status() {
		// ...
	}
}

// EOF
↳ Incorrect because `get_id()` is not first, `get_status()` not second, and `get_name()` not third. #### ~ Acceptable 
<?php

global $db_connection,
	$app_config,
	$cache;

define('MODE', 1);
define('ENVIRONMENT', 'PRODUCTION');

$id = 0;
$firstname = '';
$lastname = '';

// EOF
↳ Acceptable, but the globals and constants should be in alphabetical order. 
<?php

function get_movies() {
	// ...
}

function get_actors() {
	// ...
}

// EOF
↳ Acceptable, but `get_actors` should be declared before `get_movies`. #### ✔ Correct 
<?php

global $app_config,
	$cache,
	$db_connection;

define('ENVIRONMENT', 'PRODUCTION');
define('MODE', 1);

$id = 0;
$firstname = '';
$lastname = '';

// EOF
 

<?php

namespace MyCompany\Model;

class Office
{
	private $id;
	private $name;
	private $status;

	public function get_id() {
		// ...
	}

	protected function get_status() {
		// ...
	}

	private function get_name() {
		// ...
	}
}

// EOF
#### ✔ Preferred 
<?php

function get_actors() {
	// ...
}

function get_movies() {
	// ...
}

// EOF
▲ [Best Practices](#12-best-practices) ### 3. Globals Globals SHOULD NOT be used. #### ~ Acceptable 
<?php

$pdo = new PDO('mysql:host=localhost;dbname=test', $user, $pass);

function get_user($id) {
	global $pdo;
	// ...
}

// EOF
↳ Acceptable, but `global` variables should be avoided. #### ✔ Preferred 
<?php

function get_database_object() {
	return new PDO('mysql:host=localhost;dbname=test', $user, $pass);
}

function get_user($id) {
	$pdo = get_database_object();
	// ...
}

// EOF
▲ [Best Practices](#12-best-practices) ### 4. Explicit Expressions Explicit expressions SHOULD be used. #### ~ Acceptable 
<?php

if ($expr == true) {
	// ...
}

// EOF
↳ Acceptable, but `===` could be used here instead. #### ✔ Preferred 
<?php

if ($expr === true) {
	// ...
}

// EOF
▲ [Best Practices](#12-best-practices) ### 5. E_STRICT Reporting E_STRICT reporting MUST NOT trigger errors. #### ✖ Incorrect 
<?php

$firstname = call_user_method('get_firstname', $User);

// EOF
↳ Incorrect because `call_user_method` (deprecated) will cause E_STRICT warning. #### ✔ Correct 
<?php

$firstname = call_user_func(array($User, 'get_firstname'));

// EOF
▲ [Best Practices](#12-best-practices) --- ▲ [Table of Contents](#table-of-contents) Inspired in part by style guides from:
[CodeIgniter](http://ellislab.com/codeigniter/user-guide/general/styleguide.html), [Drupal](https://drupal.org/coding-standards), [Horde](http://www.horde.org/apps/horde/docs/CODING_STANDARDS), [Pear](http://pear.php.net/manual/en/standards.php), [PSR-1](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-1-basic-coding-standard.md), [PSR-2](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md), [Symfony](http://symfony.com/doc/current/contributing/code/standards.html), and [WordPress](http://make.wordpress.org/core/handbook/coding-standards/php/).