diff options
| -rw-r--r-- | php.html.markdown | 197 |
1 files changed, 135 insertions, 62 deletions
diff --git a/php.html.markdown b/php.html.markdown index 947ee4a7..cddba644 100644 --- a/php.html.markdown +++ b/php.html.markdown @@ -8,11 +8,14 @@ This document describes PHP 5+. ## [Basic Syntax](http://www.php.net/manual/en/language.basic-syntax.php) -All statements must end with a semi-colon; All PHP code must be between <?php and ?> tags. PHP can also be configured to respect the [short open tags](http://www.php.net/manual/en/ini.core.php#ini.short-open-tag) <? and ?>. +All statements must end with a semi-colon; All PHP code must be between <?php and ?> tags. PHP can also be +configured to respect the [short open tags](http://www.php.net/manual/en/ini.core.php#ini.short-open-tag) <? and ?>. ## [Comments](http://www.php.net/manual/en/language.basic-syntax.comments.php) ```php +<?php + // Two forward slashes start a one-line comment. # So will a hash (aka pound symbol) but // is more common @@ -25,11 +28,14 @@ All statements must end with a semi-colon; All PHP code must be between <?php an ## [Types](http://www.php.net/manual/en/language.types.php) -Types are [weakly typed](http://en.wikipedia.org/wiki/Strong_and_weak_typing) and begin with the $ symbol. A valid variable name starts with a letter or underscore, followed by any number of letters, numbers, or underscores. +Types are [weakly typed](http://en.wikipedia.org/wiki/Strong_and_weak_typing) and begin with the $ symbol. +A valid variable name starts with a letter or underscore, followed by any number of letters, numbers, or underscores. ### Scalars ```php +<?php + // Boolean values are case-insensitive $boolean = true; // or TRUE or True $boolean = false; // or FALSE or False @@ -52,20 +58,29 @@ $product = $number * $float; $quotient = $number / $float; // Shorthand arithmetic -$number += 1; // Will add 1 to $number -$number++; // Will add 1 to $number after it is used -++$number; // Will add 1 to $number before it is used. -$number /= $float // Will divide $number $float, and assign the quotient to $number - -// Strings -$sgl_quotes = 'String'; // Strings should be enclosed in single quotes; -$dbl_quotes = "This is a $sgl_quotes." // Avoid using double quotes to embed other variables -$escaped = "This contains a \t tab character."; // Escape special characters with backslash -$money = "I have $${integer} in the bank." // Enclose a variable in curly braces if needed +$number += 1; // Add 1 to $number +$number++; // Add 1 to $number after it is used +++$number; // Add 1 to $number before it is used. +$number /= $float // Divide and assign the quotient to $number + +// Strings should be enclosed in single quotes; +$sgl_quotes = '$String'; // => '$String' + +// Avoid using double quotes except to embed other variables +$dbl_quotes = "This is a $sgl_quotes." // => 'This is a $String' + +// Escape special characters with backslash +$escaped = "This contains a \t tab character."; + +// Enclose a variable in curly braces if needed +$money = "I have $${integer} in the bank." + +// Since PHP 5.3, nowdocs can be used for uninterpolated multi-liners $nowdoc = <<<'END' Multi line string END; + $heredoc = <<<END Multi line $sgl_quotes @@ -78,6 +93,8 @@ $concatenated = $sgl_quotes + $dbl_quotes; ### Compound ```php +<?php + // Arrays $array = array(1, 2, 3); $array = [1, 2, 3]; // As of PHP 5.4 @@ -92,14 +109,22 @@ $associative["One"]; // Holds the value 1 ## Output ```php -echo('Hello World!'); // Prints Hello World! to stdout. Stdout is the web page if running in a browser. +<?php + +echo('Hello World!'); +// Prints Hello World! to stdout. +// Stdout is the web page if running in a browser. + print('Hello World!'); // The same as echo -echo 'Hello World!'; // echo is actually a language construct, so you can drop the parentheses. + +// echo is actually a language construct, so you can drop the parentheses. +echo 'Hello World!'; echo 100; echo $variable; -echo function_result(); // Output the result of a function call that returns a value. More on functions later. +echo function_result(); -// If [short open tags](http://www.php.net/manual/en/ini.core.php#ini.short-open-tag) are configured, or your PHP version is 5.4.0 or greater, you can use the short echo syntax +// If short open tags are configured, or your PHP version is +// 5.4.0 or greater, you can use the short echo syntax <?= $variable ?> ``` @@ -108,21 +133,27 @@ echo function_result(); // Output the result of a function call that returns a v ### Assignment ```php +<?php + $a = 1; $b = 2; $a = $b; // A now contains the same value sa $b -$a =& $b; // A now contains a reference to $b. Changing the value of $a will change the value of $b also, and vice-versa. +$a =& $b; +// A now contains a reference to $b. Changing the value of +// $a will change the value of $b also, and vice-versa. ``` ### Comparison ```php +<?php + $a == $b // TRUE if $a is equal to $b after type juggling. $a === $b // TRUE if $a is equal to $b, and they are of the same type. $a != $b // TRUE if $a is not equal to $b after type juggling. $a <> $b // TRUE if $a is not equal to $b after type juggling. $a !== $b // TRUE if $a is not equal to $b, or they are not of the same type. -$a < $b // TRUE if $a is strictly less than $b. +$a < $b // TRUE if $a is strictly less than $b. $a > $b // TRUE if $a is strictly greater than $b. $a <= $b // TRUE if $a is less than or equal to $b. $a >= $b // TRUE if $a is greater than or equal to $b. @@ -133,14 +164,18 @@ $a >= $b // TRUE if $a is greater than or equal to $b. Variables can be converted between types, depending on their usage. ```php +<?php + $integer = 1; echo $integer + $integer; // Outputs 2; $string = '1'; -echo $string + $string; // Also outputs 2 because the + operator converts the strings to integers +echo $string + $string; +// Also outputs 2 because the + operator converts the strings to integers $string = 'one'; -echo $string + $string; // Outputs 0 because the + operator cannot cast the string 'one' to a number +echo $string + $string; +// Outputs 0 because the + operator cannot cast the string 'one' to a number $boolean = (boolean) $integer; // $boolean is true @@ -148,7 +183,8 @@ $zero = 0; $boolean = (boolean) $zero; // $boolean is false $integer = 5; -$string = strval($integer); // There are also dedicated functions for casting most types +$string = strval($integer); +// There are also dedicated functions for casting most types $var = null; // Null value ``` @@ -158,29 +194,32 @@ $var = null; // Null value ### If Statements ```php +<?php + if (/* test */) { - // Do something + // Do something } if (/* test */) { - // Do something + // Do something } else { - // Do something else + // Do something else } if (/* test */) { - // Do something + // Do something } elseif(/* test2 */) { - // Do something else, only if test2 + // Do something else, only if test2 } if (/* test */) { - // Do something + // Do something } elseif(/* test2 */) { - // Do something else, only if test2 + // Do something else, only if test2 } else { - // Do something default + // Do something default } +?> <?php if (/* test */): ?> <!-- Do something that isn't PHP --> @@ -192,16 +231,18 @@ if (/* test */) { ### Switch statements ```php +<?php + switch ($variable) { - case 'one': - // Do something if $variable == 'one' + case 'one': + // Do something if $variable == 'one' break; case 'two': case 'three': - // Do something if $variable is either 'two' or 'three' + // Do something if $variable is either 'two' or 'three' break; default: - // Do something by default + // Do something by default } ``` @@ -209,44 +250,46 @@ switch ($variable) { ### Loops ```php +<?php + $i = 0; while ($i < 5) { - echo $i++; + echo $i++; } $i = 0; do { - echo $i++; + echo $i++; } while ($i < 5); for ($x = 0; $x < 10; $x++) { - echo $x; // Will echo 0 - 9 + echo $x; // Will echo 0 - 9 } $wheels = ["bicycle" => 2, "car" => 4]; foreach ($wheels as $vehicle => $wheel_count) { - echo "A $vehicle has $wheel_count wheels"; + echo "A $vehicle has $wheel_count wheels"; } // This loop will stop after outputting 2 $i = 0; while ($i < 5) { if ($i == 3) { - break; // Exit out of the while loop and continue. + break; // Exit out of the while loop and continue. } - echo $i++; + echo $i++; } // This loop will output everything except 3 $i = 0; while ($i < 5) { - if ($i == 3) { - continue; // Skip this iteration of the loop + if ($i == 3) { + continue; // Skip this iteration of the loop } - echo $i++; + echo $i++; } ``` @@ -255,8 +298,10 @@ while ($i < 5) { Functions are created with the ```function``` keyword. ```php +<?php + function my_function($my_arg) { - $my_variable = 1; + $my_variable = 1; } // $my_variable and $my_arg cannot be accessed outside of the function @@ -265,23 +310,28 @@ function my_function($my_arg) { Functions may be invoked by name. ```php +<?php + my_function_name(); $variable = get_something(); // A function may return a value ``` -A valid function name starts with a letter or underscore, followed by any number of letters, numbers, or underscores. There are three ways to declare functions. +A valid function name starts with a letter or underscore, followed by any +number of letters, numbers, or underscores. There are three ways to declare functions. ### [User-defined](http://www.php.net/manual/en/functions.user-defined.php) ```php +<?php + function my_function_name ($arg_1, $arg_2) { // $arg_1 and $arg_2 are required - // Do something with $arg_1 and $arg_2; + // Do something with $arg_1 and $arg_2; } // Functions may be nested to limit scope function outer_function ($arg_1 = null) { // $arg_1 is optional - function inner_function($arg_2 = 'two') { // $arg_2 will default to 'two' + function inner_function($arg_2 = 'two') { // $arg_2 will default to 'two' } } @@ -291,6 +341,8 @@ function outer_function ($arg_1 = null) { // $arg_1 is optional ### [Variable](http://www.php.net/manual/en/functions.variable-functions.php) ```php +<?php + $function_name = 'my_function_name'; $function_name(); // will execute the my_function_name() function @@ -301,13 +353,15 @@ $function_name(); // will execute the my_function_name() function Similar to variable functions, functions may be anonymous. ```php +<?php + my_function(function () { - // do something + // do something }); // Closure style $my_function = function() { - // Do something + // Do something }; $my_function(); @@ -318,10 +372,12 @@ $my_function(); Classes are defined with the ```class``` keyword. ```php +<?php + class MyClass { - const MY_CONST = 'value'; + const MY_CONST = 'value'; static $staticVar = 'something'; - public $property = 'value'; // Properties must declare their visibility + public $property = 'value'; // Properties must declare their visibility } echo MyClass::MY_CONST; // Outputs "value"; @@ -330,11 +386,14 @@ final class YouCannotExtendMe { } ``` -Classes are insantiated with the ```new``` keyword. Functions are referred to as methods if they belong to a class. +Classes are insantiated with the ```new``` keyword. Functions are referred to as +methods if they belong to a class. ```php +<?php + class MyClass { - function myFunction() { + function myFunction() { } function function youCannotOverrideMe() @@ -358,36 +417,40 @@ MyClass::myStaticMethod(); // myStaticMethod cannot be run on $cls PHP offers some [magic methods](http://www.php.net/manual/en/language.oop5.magic.php) for classes. ```php +<?php + class MyClass { - private $property; + private $property; public function __get($key) { - return $this->$key; + return $this->$key; } public function __set($key, $value) { - $this->$key = $value; + $this->$key = $value; } } $x = new MyClass(); -echo $x->property; // Will use the __get() method to retrieve the value of $property -$x->property = 'Something'; // Will use the __set() method to set the value of property +echo $x->property; // Will use the __get() method +$x->property = 'Something'; // Will use the __set() method ``` Classes can be abstract (using the ```abstract``` keyword), extend other classes (using the ```extends``` keyword) and implement interfaces (using the ```implements``` keyword). An interface is declared with the ```interface``` keyword. ```php +<?php + interface InterfaceOne { - public function doSomething(); + public function doSomething(); } interface InterfaceTwo { - public function doSomething(); + public function doSomething(); } abstract class MyAbstractClass implements InterfaceOne @@ -409,10 +472,14 @@ class SomeOtherClass implements InterfaceOne, InterfaceTwo By default, classes exist in the global namespace, and can be explicitly called with a backslash. ```php +<?php + $cls = new \MyClass(); ``` ```php +<?php + namespace My\Namespace; class MyClass @@ -425,6 +492,8 @@ $cls = new My\Namespace\MyClass; Or from within another namespace. ```php +<?php + namespace My\Other\Namespace; use My\Namespace\MyClass; @@ -435,6 +504,8 @@ $cls = new MyClass(); Or you can alias the namespace; ```php +<?php + namespace My\Other\Namespace; use My\Namespace as SomeOtherNamespace; @@ -447,16 +518,18 @@ $cls = new SomeOtherNamespace\MyClass(); Traits are available since PHP 5.4.0 and are declared using the ```trait``` keyword. ```php +<?php + trait MyTrait { - public function myTraitMethod() + public function myTraitMethod() { - // Do something + // Do something } } class MyClass { - use MyTrait; + use MyTrait; } $cls = new MyClass(); |