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- <?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 prevent accidental output.
- // Two forward slashes start a one-line comment.
- # So will a hash (aka pound symbol) but // is more common
- /*
- Surrounding text in slash-asterisk and asterisk-slash
- makes it a multi-line comment.
- */
- // Use "echo" or "print" to print output
- print('Hello '); // Prints "Hello " with no line break
- // () are optional for print and echo
- echo "World\n"; // Prints "World" with a line break
- // (all statements must end with a semicolon)
- // Anything outside <?php tags is echoed automatically
- ?>
- Hello World Again!
- <?php
- /************************************
- * Types & Variables
- */
- // Variables begin with the $ symbol.
- // A valid variable name starts with a letter or underscore,
- // followed by any number of letters, numbers, or underscores.
- // Boolean values are case-insensitive
- $boolean = true; // or TRUE or True
- $boolean = false; // or FALSE or False
- // Integers
- $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;
- $float = 1.2e3;
- $float = 7E-10;
- // Delete variable
- unset($int1);
- // Arithmetic
- $sum = 1 + 1; // 2
- $difference = 2 - 1; // 1
- $product = 2 * 2; // 4
- $quotient = 2 / 1; // 2
- // Shorthand arithmetic
- $number = 0;
- $number += 1; // Increment $number by 1
- echo $number++; // Prints 1 (increments after evaluation)
- echo ++$number; // Prints 3 (increments before evaluation)
- $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.'
- // Special characters are only escaped in double quotes
- $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
- $nowdoc = <<<'END'
- Multi line
- string
- END;
- // Heredocs will do string interpolation
- $heredoc = <<<END
- Multi line
- $sgl_quotes
- 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
- */
- // A constant is defined by using define()
- // and can never be changed during runtime!
- // a valid constant name starts with a letter or underscore,
- // followed by any number of letters, numbers, or underscores.
- define("FOO", "something");
- // access to a constant is possible by calling the choosen name without a $
- echo FOO; // Returns 'something'
- echo 'This outputs ' . FOO; // Returns 'This ouputs something'
- /********************************
- * Arrays
- */
- // All arrays in PHP are associative arrays (hashmaps),
- // Associative arrays, known as hashmaps in some languages.
- // Works with all PHP versions
- $associative = array('One' => 1, 'Two' => 2, 'Three' => 3);
- // PHP 5.4 introduced a new syntax
- $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]);
- /********************************
- * Output
- */
- 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 and print are language constructs too, so you can drop the parentheses
- echo 'Hello World!';
- print 'Hello World!';
- $paragraph = 'paragraph';
- echo 100; // Echo scalar variables directly
- echo $paragraph; // or variables
- // If short open tags are configured, or your PHP version is
- // 5.4.0 or greater, you can use the short echo syntax
- ?>
- <p><?= $paragraph ?></p>
- <?php
- $x = 1;
- $y = 2;
- $x = $y; // $x now contains the same value as $y
- $z = &$y;
- // $z now contains a reference to $y. Changing the value of
- // $z will change the value of $y also, and vice-versa.
- // $x will remain unchanged as the original value of $y
- echo $x; // => 2
- echo $z; // => 2
- $y = 0;
- echo $x; // => 2
- echo $z; // => 0
- // Dumps type and value of variable to stdout
- var_dump($z); // prints int(0)
- // Prints variable to stdout in human-readable format
- print_r($array); // prints: Array ( [0] => One [1] => Two [2] => Three )
- /********************************
- * Logic
- */
- $a = 0;
- $b = '0';
- $c = '1';
- $d = '1';
- // assert throws a warning if its argument is not true
- // These comparisons will always be true, even if the types aren't the same.
- assert($a == $b); // equality
- assert($c != $a); // inequality
- assert($c <> $a); // alternative inequality
- assert($a < $c);
- assert($c > $b);
- assert($a <= $b);
- assert($c >= $d);
- // The following will only be true if the values match and are the same type.
- assert($c === $d);
- assert($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;
- echo $integer + $integer; // => 2
- $string = '1';
- echo $string + $string; // => 2 (strings are coerced to integers)
- $string = 'one';
- echo $string + $string; // => 0
- // Outputs 0 because the + operator cannot cast the string 'one' to a number
- // Type casting can be used to treat a variable as another type
- $boolean = (boolean) 1; // => true
- $zero = 0;
- $boolean = (boolean) $zero; // => false
- // There are also dedicated functions for casting most types
- $integer = 5;
- $string = strval($integer);
- $var = null; // Null value
- /********************************
- * Control Structures
- */
- if (true) {
- print 'I get printed';
- }
- if (false) {
- print 'I don\'t';
- } else {
- print 'I get printed';
- }
- if (false) {
- print 'Does not get printed';
- } elseif (true) {
- print 'Does';
- }
- // ternary operator
- print (false ? 'Does not get printed' : 'Does');
- // ternary shortcut operator since PHP 5.3
- // equivalent of "$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 ($x == '1') {
- print 'Does not print';
- } else {
- print 'Does print';
- }
- // This alternative syntax is useful for templates:
- ?>
- <?php if ($x): ?>
- This is displayed if the test is truthy.
- <?php else: ?>
- This is displayed otherwise.
- <?php endif; ?>
- <?php
- // Use switch to save some logic.
- switch ($x) {
- case '0':
- print 'Switch does type coercion';
- break; // You must include a break, or you will fall through
- // to cases 'two' and 'three'
- case 'two':
- case 'three':
- // Do something if $variable is either 'two' or 'three'
- break;
- default:
- // Do something by default
- }
- // While, do...while and for loops are probably familiar
- $i = 0;
- while ($i < 5) {
- echo $i++;
- }; // Prints "01234"
- echo "\n";
- $i = 0;
- do {
- echo $i++;
- } while ($i < 5); // Prints "01234"
- echo "\n";
- for ($x = 0; $x < 10; $x++) {
- echo $x;
- } // Prints "0123456789"
- echo "\n";
- $wheels = ['bicycle' => 2, 'car' => 4];
- // Foreach loops can iterate over arrays
- foreach ($wheels as $wheel_count) {
- echo $wheel_count;
- } // Prints "24"
- echo "\n";
- // You can iterate over the keys as well as the values
- foreach ($wheels as $vehicle => $wheel_count) {
- echo "A $vehicle has $wheel_count wheels";
- }
- echo "\n";
- $i = 0;
- while ($i < 5) {
- if ($i === 3) {
- break; // Exit out of the while loop
- }
- echo $i++;
- } // Prints "012"
- for ($i = 0; $i < 5; $i++) {
- if ($i === 3) {
- continue; // Skip this iteration of the loop
- }
- echo $i;
- } // Prints "0124"
- /********************************
- * Functions
- */
- // Define a function with "function":
- function my_function () {
- return 'Hello';
- }
- echo my_function(); // => "Hello"
- // A valid function name starts with a letter or underscore, followed by any
- // number of letters, numbers, or underscores.
- function add ($x, $y = 1) { // $y is optional and defaults to 1
- $result = $x + $y;
- return $result;
- }
- echo add(4); // => 5
- echo add(4, 2); // => 6
- // $result is not accessible outside the function
- // print $result; // Gives a warning.
- // Since PHP 5.3 you can declare anonymous functions;
- $inc = function ($x) {
- return $x + 1;
- };
- echo $inc(2); // => 3
- function foo ($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);
- };
- }
- $bar = bar('A', 'B');
- $bar('C'); // Prints "A - B - C"
- // You can call named functions using strings
- $function_name = 'add';
- 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
- */
- <?php
- // PHP within included files must also begin with a PHP open tag.
- include 'my-file.php';
- // The code in my-file.php is now available in the current scope.
- // If the file cannot be included (e.g. file not found), a warning is emitted.
- include_once 'my-file.php';
- // If the code in my-file.php has been included elsewhere, it will
- // not be included again. This prevents multiple class declaration errors
- require 'my-file.php';
- require_once 'my-file.php';
- // Same as include(), except require() will cause a fatal error if the
- // file cannot be included.
- // Contents of my-include.php:
- <?php
- return 'Anything you like.';
- // End file
- // Includes and requires may also return a value.
- $value = include 'my-include.php';
- // Files are included based on the file path given or, if none is given,
- // the include_path configuration directive. If the file isn't found in
- // the include_path, include will finally check in the calling script's
- // own directory and the current working directory before failing.
- /* */
- /********************************
- * Classes
- */
- // Classes are defined with the class keyword
- class MyClass
- {
- const MY_CONST = 'value'; // A constant
- static $staticVar = 'static';
- // Static variables and their visibility
- public static $publicStaticVar = 'publicStatic';
- // Accessible within the class only
- private static $privateStaticVar = 'privateStatic';
- // Accessible from the class and subclasses
- protected static $protectedStaticVar = 'protectedStatic';
- // Properties must declare their visibility
- public $property = 'public';
- public $instanceProp;
- protected $prot = 'protected'; // Accessible from the class and subclasses
- private $priv = 'private'; // Accessible within the class only
- // Create a constructor with __construct
- public function __construct($instanceProp)
- {
- // Access instance variables with $this
- $this->instanceProp = $instanceProp;
- }
- // Methods are declared as functions inside a class
- public function myMethod()
- {
- print 'MyClass';
- }
- // 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 $property;
- }
- // opposite to __construct()
- // called when object is no longer referenced
- public function __destruct()
- {
- print "Destroying";
- }
- /*
- * Declaring class properties or methods as static makes them accessible without
- * needing an instantiation of the class. A property declared as static can not
- * be accessed with an instantiated class object (though a static method can).
- */
- public static function myStaticMethod()
- {
- print 'I am static';
- }
- }
- // Class constants can always be accessed statically
- echo MyClass::MY_CONST; // Outputs 'value';
- echo MyClass::$staticVar; // Outputs 'static';
- MyClass::myStaticMethod(); // Outputs 'I am static';
- // Instantiate classes using new
- $my_class = new MyClass('An instance property');
- // The parentheses are optional if not passing in an argument.
- // Access class members using ->
- echo $my_class->property; // => "public"
- echo $my_class->instanceProp; // => "An instance property"
- $my_class->myMethod(); // => "MyClass"
- // Extend classes using "extends"
- class MyOtherClass extends MyClass
- {
- function printProtectedProperty()
- {
- echo $this->prot;
- }
- // Override a method
- function myMethod()
- {
- parent::myMethod();
- print ' > MyOtherClass';
- }
- }
- $my_other_class = new MyOtherClass('Instance prop');
- $my_other_class->printProtectedProperty(); // => Prints "protected"
- $my_other_class->myMethod(); // Prints "MyClass > MyOtherClass"
- final class YouCannotExtendMe
- {
- }
- // You can use "magic methods" to create getters and setters
- class MyMapClass
- {
- private $property;
- public function __get($key)
- {
- return $this->$key;
- }
- public function __set($key, $value)
- {
- $this->$key = $value;
- }
- }
- $x = new MyMapClass();
- echo $x->property; // Will use the __get() method
- $x->property = 'Something'; // Will use the __set() method
- // Classes can be abstract (using the abstract keyword) or
- // implement interfaces (using the implements keyword).
- // An interface is declared with the interface keyword.
- interface InterfaceOne
- {
- public function doSomething();
- }
- interface InterfaceTwo
- {
- public function doSomethingElse();
- }
- // interfaces can be extended
- interface InterfaceThree extends InterfaceTwo
- {
- public function doAnotherContract();
- }
- abstract class MyAbstractClass implements InterfaceOne
- {
- public $x = 'doSomething';
- }
- class MyConcreteClass extends MyAbstractClass implements InterfaceTwo
- {
- public function doSomething()
- {
- echo $x;
- }
- public function doSomethingElse()
- {
- echo 'doSomethingElse';
- }
- }
- // Classes can implement more than one interface
- class SomeOtherClass implements InterfaceOne, InterfaceTwo
- {
- public function doSomething()
- {
- echo 'doSomething';
- }
- public function doSomethingElse()
- {
- echo 'doSomethingElse';
- }
- }
- /********************************
- * Traits
- */
- // Traits are available from PHP 5.4.0 and are declared using "trait"
- trait MyTrait
- {
- public function myTraitMethod()
- {
- print 'I have MyTrait';
- }
- }
- class MyTraitfulClass
- {
- use MyTrait;
- }
- $cls = new MyTraitfulClass();
- $cls->myTraitMethod(); // Prints "I have MyTrait"
- /********************************
- * Namespaces
- */
- // This section is separate, because a namespace declaration
- // must be the first statement in a file. Let's pretend that is not the case
- <?php
- // By default, classes exist in the global namespace, and can
- // be explicitly called with a backslash.
- $cls = new \MyClass();
- // Set the namespace for a file
- namespace My\Namespace;
- class MyClass
- {
- }
- // (from another file)
- $cls = new My\Namespace\MyClass;
- //Or from within another namespace.
- namespace My\Other\Namespace;
- use My\Namespace\MyClass;
- $cls = new MyClass();
- // Or you can alias the namespace;
- namespace My\Other\Namespace;
- 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 enviroment 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 happend');
- }
- } catch (MyException $e) {
- // Handle my exception
- }
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