diff options
Diffstat (limited to 'php.html.markdown')
| -rw-r--r-- | php.html.markdown | 238 |
1 files changed, 213 insertions, 25 deletions
diff --git a/php.html.markdown b/php.html.markdown index 039288a0..f82cea7d 100644 --- a/php.html.markdown +++ b/php.html.markdown @@ -12,7 +12,7 @@ This document describes PHP 5+. <?php // PHP code must be enclosed with <?php tags // If your php file only contains PHP code, it is best practice -// to omit the php closing tag. +// to omit the php closing tag to prevent accidental output. // Two forward slashes start a one-line comment. @@ -53,6 +53,8 @@ $int1 = 12; // => 12 $int2 = -12; // => -12 $int3 = 012; // => 10 (a leading 0 denotes an octal number) $int4 = 0x0F; // => 15 (a leading 0x denotes a hex literal) +// Binary integer literals are available since PHP 5.4.0. +$int5 = 0b11111111; // 255 (a leading 0b denotes a binary number) // Floats (aka doubles) $float = 1.234; @@ -60,7 +62,7 @@ $float = 1.2e3; $float = 7E-10; // Delete variable -unset($int1) +unset($int1); // Arithmetic $sum = 1 + 1; // 2 @@ -86,6 +88,8 @@ $escaped = "This contains a \t tab character."; $unescaped = 'This just contains a slash and a t: \t'; // Enclose a variable in curly braces if needed +$apples = "I have {$number} apples to eat."; +$oranges = "I have ${number} oranges to eat."; $money = "I have $${number} in the bank."; // Since PHP 5.3, nowdocs can be used for uninterpolated multi-liners @@ -103,6 +107,9 @@ END; // String concatenation is done with . echo 'This string ' . 'is concatenated'; +// Strings can be passed in as parameters to echo +echo 'Multiple', 'Parameters', 'Valid'; // Returns 'MultipleParametersValid' + /******************************** * Constants @@ -113,19 +120,19 @@ echo 'This string ' . 'is concatenated'; // a valid constant name starts with a letter or underscore, // followed by any number of letters, numbers, or underscores. -define("FOO", "something"); +define("FOO", "something"); + +// access to a constant is possible by calling the chosen name without a $ +echo FOO; // Returns 'something' +echo 'This outputs ' . FOO; // Returns 'This outputs something' -// access to a constant is possible by direct using the choosen name -echo 'This outputs '.FOO; /******************************** * Arrays */ -// All arrays in PHP are associative arrays (hashmaps), - -// Associative arrays, known as hashmaps in some languages. +// All arrays in PHP are associative arrays (hashmaps in some languages) // Works with all PHP versions $associative = array('One' => 1, 'Two' => 2, 'Three' => 3); @@ -135,12 +142,17 @@ $associative = ['One' => 1, 'Two' => 2, 'Three' => 3]; echo $associative['One']; // prints 1 +// Add an element to an associative array +$associative['Four'] = 4; + // List literals implicitly assign integer keys $array = ['One', 'Two', 'Three']; echo $array[0]; // => "One" // Add an element to the end of an array $array[] = 'Four'; +// or +array_push($array, 'Five'); // Remove element from array unset($array[3]); @@ -155,9 +167,9 @@ echo('Hello World!'); print('Hello World!'); // The same as echo -// echo is actually a language construct, so you can drop the parentheses. +// echo and print are language constructs too, so you can drop the parentheses echo 'Hello World!'; -print 'Hello World!'; // So is print +print 'Hello World!'; $paragraph = 'paragraph'; @@ -215,6 +227,18 @@ assert($a !== $d); assert(1 === '1'); assert(1 !== '1'); +// 'Spaceship' operator (since PHP 7) +// Returns 0 if values on either side are equal +// Returns 1 if value on the left is greater +// Returns -1 if the value on the right is greater + +$a = 100; +$b = 1000; + +echo $a <=> $a; // 0 since they are equal +echo $a <=> $b; // -1 since $a < $b +echo $b <=> $a; // 1 since $b > $a + // Variables can be converted between types, depending on their usage. $integer = 1; @@ -257,17 +281,29 @@ if (false) { if (false) { print 'Does not get printed'; -} elseif(true) { +} elseif (true) { print 'Does'; } // ternary operator print (false ? 'Does not get printed' : 'Does'); +// ternary shortcut operator since PHP 5.3 +// equivalent of "$x ? $x : 'Does'"" +$x = false; +print($x ?: 'Does'); + +// null coalesce operator since php 7 +$a = null; +$b = 'Does print'; +echo $a ?? 'a is not set'; // prints 'a is not set' +echo $b ?? 'b is not set'; // prints 'Does print' + + $x = 0; if ($x === '0') { print 'Does not print'; -} elseif($x == '1') { +} elseif ($x == '1') { print 'Does not print'; } else { print 'Does print'; @@ -304,7 +340,7 @@ switch ($x) { $i = 0; while ($i < 5) { echo $i++; -}; // Prints "01234" +} // Prints "01234" echo "\n"; @@ -359,7 +395,7 @@ for ($i = 0; $i < 5; $i++) { // Define a function with "function": function my_function () { - return 'Hello'; + return 'Hello'; } echo my_function(); // => "Hello" @@ -368,8 +404,8 @@ echo my_function(); // => "Hello" // number of letters, numbers, or underscores. function add ($x, $y = 1) { // $y is optional and defaults to 1 - $result = $x + $y; - return $result; + $result = $x + $y; + return $result; } echo add(4); // => 5 @@ -380,21 +416,21 @@ echo add(4, 2); // => 6 // Since PHP 5.3 you can declare anonymous functions; $inc = function ($x) { - return $x + 1; + return $x + 1; }; echo $inc(2); // => 3 function foo ($x, $y, $z) { - echo "$x - $y - $z"; + echo "$x - $y - $z"; } // Functions can return functions function bar ($x, $y) { - // Use 'use' to bring in outside variables - return function ($z) use ($x, $y) { - foo($x, $y, $z); - }; + // Use 'use' to bring in outside variables + return function ($z) use ($x, $y) { + foo($x, $y, $z); + }; } $bar = bar('A', 'B'); @@ -406,6 +442,31 @@ echo $function_name(1, 2); // => 3 // Useful for programatically determining which function to run. // Or, use call_user_func(callable $callback [, $parameter [, ... ]]); + +// You can get the all the parameters passed to a function +function parameters() { + $numargs = func_num_args(); + if ($numargs > 0) { + echo func_get_arg(0) . ' | '; + } + $args_array = func_get_args(); + foreach ($args_array as $key => $arg) { + echo $key . ' - ' . $arg . ' | '; + } +} + +parameters('Hello', 'World'); // Hello | 0 - Hello | 1 - World | + +// Since PHP 5.6 you can get a variable number of arguments +function variable($word, ...$list) { + echo $word . " || "; + foreach ($list as $item) { + echo $item . ' | '; + } +} + +variable("Separate", "Hello", "World"); // Separate || Hello | World | + /******************************** * Includes */ @@ -467,7 +528,8 @@ class MyClass private $priv = 'private'; // Accessible within the class only // Create a constructor with __construct - public function __construct($instanceProp) { + public function __construct($instanceProp) + { // Access instance variables with $this $this->instanceProp = $instanceProp; } @@ -478,16 +540,31 @@ class MyClass print 'MyClass'; } - //final keyword would make a function unoverridable + // final keyword would make a function unoverridable final function youCannotOverrideMe() { } + // Magic Methods + + // what to do if Object is treated as a String + public function __toString() + { + return $property; + } + + // opposite to __construct() + // called when object is no longer referenced + public function __destruct() + { + print "Destroying"; + } + /* * Declaring class properties or methods as static makes them accessible without * needing an instantiation of the class. A property declared as static can not * be accessed with an instantiated class object (though a static method can). -*/ + */ public static function myStaticMethod() { @@ -495,7 +572,9 @@ class MyClass } } +// Class constants can always be accessed statically echo MyClass::MY_CONST; // Outputs 'value'; + echo MyClass::$staticVar; // Outputs 'static'; MyClass::myStaticMethod(); // Outputs 'I am static'; @@ -671,8 +750,117 @@ use My\Namespace as SomeOtherNamespace; $cls = new SomeOtherNamespace\MyClass(); + +/********************** +* Late Static Binding +* */ +class ParentClass +{ + public static function who() + { + echo "I'm a " . __CLASS__ . "\n"; + } + + public static function test() + { + // self references the class the method is defined within + self::who(); + // static references the class the method was invoked on + static::who(); + } +} + +ParentClass::test(); +/* +I'm a ParentClass +I'm a ParentClass +*/ + +class ChildClass extends ParentClass +{ + public static function who() + { + echo "But I'm " . __CLASS__ . "\n"; + } +} + +ChildClass::test(); +/* +I'm a ParentClass +But I'm ChildClass +*/ + +/********************** +* Magic constants +* +*/ + +// Get current class name. Must be used inside a class declaration. +echo "Current class name is " . __CLASS__; + +// Get full path directory of a file +echo "Current directory is " . __DIR__; + + // Typical usage + require __DIR__ . '/vendor/autoload.php'; + +// Get full path of a file +echo "Current file path is " . __FILE__; + +// Get current function name +echo "Current function name is " . __FUNCTION__; + +// Get current line number +echo "Current line number is " . __LINE__; + +// Get the name of the current method. Only returns a value when used inside a trait or object declaration. +echo "Current method is " . __METHOD__; + +// Get the name of the current namespace +echo "Current namespace is " . __NAMESPACE__; + +// Get the name of the current trait. Only returns a value when used inside a trait or object declaration. +echo "Current trait is " . __TRAIT__; + +/********************** +* Error Handling +* +*/ + +// Simple error handling can be done with try catch block + +try { + // Do something +} catch (Exception $e) { + // Handle exception +} + +// When using try catch blocks in a namespaced environment use the following + +try { + // Do something +} catch (\Exception $e) { + // Handle exception +} + +// Custom exceptions + +class MyException extends Exception {} + +try { + + $condition = true; + + if ($condition) { + throw new MyException('Something just happened'); + } + +} catch (MyException $e) { + // Handle my exception +} + ``` ## More Information |