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-rw-r--r--php.html.markdown232
1 files changed, 154 insertions, 78 deletions
diff --git a/php.html.markdown b/php.html.markdown
index 1a8dea2c..9627035c 100644
--- a/php.html.markdown
+++ b/php.html.markdown
@@ -1,7 +1,9 @@
---
language: php
-author: Malcolm Fell
-author_url: http://emarref.net/
+contributors:
+- [Malcolm Fell](http://emarref.net/)
+- [Trismegiste](https://github.com/Trismegiste)
+filename: learnphp.php
---
This document describes PHP 5+.
@@ -9,6 +11,9 @@ This document describes PHP 5+.
```php
<?php // PHP code must be enclosed with <?php ? > tags
+// If your php file only contains PHP code, it is best practise
+// to omit the php closing tag.
+
// Two forward slashes start a one-line comment.
# So will a hash (aka pound symbol) but // is more common
@@ -22,7 +27,7 @@ This document describes PHP 5+.
print('Hello '); // Prints "Hello " with no line break
// () are optional for print and echo
-echo 'World\n'; // Prints "World" with a line break
+echo "World\n"; // Prints "World" with a line break
// (all statements must end with a semicolon)
// Anything outside <?php tags is echoed automatically
@@ -39,13 +44,13 @@ echo 'World\n'; // Prints "World" with a line break
// followed by any number of letters, numbers, or underscores.
// Boolean values are case-insensitive
-$boolean = true; // or TRUE or True
+$boolean = true; // or TRUE or True
$boolean = false; // or FALSE or False
// Integers
-$int1 = 19; // => 19
-$int2 = -19; // => -19
-$int3 = 019; // => 15 (a leading 0 denotes an octal number)
+$int1 = 12; // => 12
+$int2 = -12; // => -12
+$int3 = 012; // => 10 (a leading 0 denotes an octal number)
$int4 = 0x0F; // => 15 (a leading 0x denotes a hex literal)
// Floats (aka doubles)
@@ -54,26 +59,26 @@ $float = 1.2e3;
$float = 7E-10;
// Arithmetic
-$sum = 1 + 1; // 2
+$sum = 1 + 1; // 2
$difference = 2 - 1; // 1
-$product = 2 * 2; // 4
-$quotient = 2 / 1; // 2
+$product = 2 * 2; // 4
+$quotient = 2 / 1; // 2
// Shorthand arithmetic
$number = 0;
-$number += 1; // Add 1 to $number
-echo $number++; // Prints 1 (increments after evaluation)
-echo ++$number; // Prints 3 (increments before evalutation)
+$number += 1; // Increment $number by 1
+echo $number++; // Prints 1 (increments after evaluation)
+echo ++$number; // Prints 3 (increments before evalutation)
$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 $String'
+$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.";
+$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
@@ -109,7 +114,7 @@ $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"
+echo $associative['One']; // prints 1
// List literals implicitly assign integer keys
$array = ['One', 'Two', 'Three'];
@@ -132,8 +137,8 @@ print 'Hello World!'; // So is print
$paragraph = 'paragraph';
-echo 100;
-echo $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
@@ -143,10 +148,11 @@ echo $paragraph;
$x = 1;
$y = 2;
-$x = $y; // A now contains the same value sa $y
+$x = $y; // $x now contains the same value as $y
$z = &$y;
-// $x now contains a reference to $y. Changing the value of
-// $x will change the value of $y also, and vice-versa.
+// $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
@@ -167,8 +173,8 @@ $d = '1';
// These comparisons will always be true, even if the types aren't the same.
assert($a == $b); // equality
-assert($b != $a); // inequality
-assert($a <> $b); // alternative inequality
+assert($c != $a); // inequality
+assert($c <> $a); // alternative inequality
assert($a < $c);
assert($c > $b);
assert($a <= $b);
@@ -215,7 +221,7 @@ if (true) {
}
if (false) {
- print "I don't";
+ print 'I don\'t';
} else {
print 'I get printed';
}
@@ -226,6 +232,9 @@ if (false) {
print 'Does';
}
+// ternary operator
+print (false ? 'Does not get printed' : 'Does');
+
$x = 0;
if ($x === '0') {
print 'Does not print';
@@ -235,6 +244,8 @@ if ($x === '0') {
print 'Does print';
}
+
+
// This alternative syntax is useful for templates:
?>
@@ -251,6 +262,7 @@ switch ($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 $variable is either 'two' or 'three'
@@ -275,16 +287,16 @@ do {
echo "\n";
for ($x = 0; $x < 10; $x++) {
- echo $x; // Will echo 0 - 9
-}// Prints "0123456789"
+ 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";
+foreach ($wheels as $wheel_count) {
+ echo $wheel_count;
} // Prints "24"
echo "\n";
@@ -302,9 +314,9 @@ while ($i < 5) {
break; // Exit out of the while loop
}
echo $i++;
-}// Prints "012"
+} // Prints "012"
-for($i = 0; $i < 5; $i++){
+for ($i = 0; $i < 5; $i++) {
if ($i === 3) {
continue; // Skip this iteration of the loop
}
@@ -317,7 +329,7 @@ for($i = 0; $i < 5; $i++){
*/
// Define a function with "function":
-function my_function() {
+function my_function () {
return 'Hello';
}
@@ -326,7 +338,7 @@ echo my_function(); // => "Hello"
// A valid function name starts with a letter or underscore, followed by any
// number of letters, numbers, or underscores.
-function add($x, $y = 1) { // $y is optional, and defaults to 2
+function add ($x, $y = 1) { // $y is optional and defaults to 1
$result = $x + $y;
return $result;
}
@@ -338,7 +350,7 @@ echo add(4, 2); // => 6
// print $result; // Gives a warning.
// Since PHP 5.3 you can declare anonymous functions;
-$inc = function($x){
+$inc = function ($x) {
return $x + 1;
};
@@ -357,78 +369,130 @@ function bar ($x, $y) {
}
$bar = bar('A', 'B');
-$bar('C');
+$bar('C'); // Prints "A - B - C"
// You can call named functions using strings
$function_name = 'add';
echo $function_name(1, 2); // => 3
-// But, you should probably use anonymous functions instead.
+// Useful for programatically determining which function to run.
+// Or, use call_user_func(callable $callback [, $parameter [, ... ]]);
+
+/********************************
+ * Includes
+ */
+
+<?php
+// PHP within included files must also begin with a PHP open tag.
+
+include 'my-file.php';
+// The code in my-file.php is now available in the current scope.
+// If the file cannot be included (e.g. file not found), a warning is emitted.
+
+include_once 'my-file.php';
+// If the code in my-file.php has been included elsewhere, it will
+// not be included again. This prevents multiple class declaration errors
+
+require 'my-file.php';
+require_once 'my-file.php';
+// Same as include(), except require() will cause a fatal error if the
+// file cannot be included.
+
+// Contents of my-include.php:
+<?php
+
+return 'Anything you like.';
+// End file
+
+// Includes and requires may also return a value.
+$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
+// Classes are defined with the class keyword
-class MyClass {
- const MY_CONST = 'value'; // A constant
- static $staticVar = 'static';
- public $property = 'public'; // Properties must declare their visibility
- private $privprop = 'private'; // Accessible within the class only
- protected $protprop = 'protected'; // Accessible within the class and subclasses
+class MyClass
+{
+ const MY_CONST = 'value'; // A constant
+
+ static $staticVar = 'static';
+
+ // 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){
+ public function __construct($instanceProp) {
// Access instance variables with $this
$this->instanceProp = $instanceProp;
}
+
// Methods are declared as functions inside a class
- public function myMethod() {
- print "MyClass";
+ public function myMethod()
+ {
+ print 'MyClass';
}
- final function youCannotOverrideMe() {
+ final function youCannotOverrideMe()
+ {
}
- public static function myStaticMethod() {
- print "I am static";
+ public static function myStaticMethod()
+ {
+ print 'I am static';
}
}
-echo MyClass::MY_CONST; // Outputs "value";
-echo MyClass::$staticVar; // Outputs 'static';
-MyClass::myStaticMethod(); // Outputs "I am static";
+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 ->.
-$my_class = new MyClass("An instance property"); // The parentheses are optional.
-echo $my_class->property; // => "public"
+// Access class members using ->
+echo $my_class->property; // => "public"
echo $my_class->instanceProp; // => "An instance property"
-$my_class->myMethod(); // => "MyClass"
+$my_class->myMethod(); // => "MyClass"
// Extend classes using "extends"
-class MyOtherClass extends MyClass{
- function printProtectedProperty(){
- echo $this->protprop;
+class MyOtherClass extends MyClass
+{
+ function printProtectedProperty()
+ {
+ echo $this->prot;
}
// Override a method
- function myMethod() {
+ function myMethod()
+ {
parent::myMethod();
- print " > MyOtherClass";
+ print ' > MyOtherClass';
}
}
-$my_other_class = new MyOtherClass("Instance prop");
+$my_other_class = new MyOtherClass('Instance prop');
$my_other_class->printProtectedProperty(); // => Prints "protected"
-$my_other_class->myMethod(); // Prints "MyClass > MyOtherClass"
+$my_other_class->myMethod(); // Prints "MyClass > MyOtherClass"
-final class YouCannotExtendMe {
+final class YouCannotExtendMe
+{
}
// You can use "magic methods" to create getters and setters
-class MyMapClass {
+class MyMapClass
+{
private $property;
public function __get($key)
@@ -460,18 +524,27 @@ interface InterfaceTwo
public function doSomethingElse();
}
+// interfaces can be extended
+interface InterfaceThree extends InterfaceTwo
+{
+ public function doAnotherContract();
+}
+
abstract class MyAbstractClass implements InterfaceOne
{
- public $x = "doSomething";
+ public $x = 'doSomething';
}
class MyConcreteClass extends MyAbstractClass implements InterfaceTwo
{
- public function doSomething(){
+ public function doSomething()
+ {
echo $x;
}
- public function doSomethingElse(){
- echo "doSomethingElse";
+
+ public function doSomethingElse()
+ {
+ echo 'doSomethingElse';
}
}
@@ -479,11 +552,14 @@ class MyConcreteClass extends MyAbstractClass implements InterfaceTwo
// Classes can implement more than one interface
class SomeOtherClass implements InterfaceOne, InterfaceTwo
{
- public function doSomething(){
- echo "doSomething";
+ public function doSomething()
+ {
+ echo 'doSomething';
}
- public function doSomethingElse(){
- echo "doSomethingElse";
+
+ public function doSomethingElse()
+ {
+ echo 'doSomethingElse';
}
}
@@ -492,12 +568,13 @@ class SomeOtherClass implements InterfaceOne, InterfaceTwo
* Traits
*/
-//Traits are available since PHP 5.4.0 and are declared using the trait keyword.
+// Traits are available from PHP 5.4.0 and are declared using "trait"
-trait MyTrait {
+trait MyTrait
+{
public function myTraitMethod()
{
- print "I have MyTrait";
+ print 'I have MyTrait';
}
}
@@ -517,9 +594,6 @@ $cls->myTraitMethod(); // Prints "I have MyTrait"
// 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
<?php
// By default, classes exist in the global namespace, and can
@@ -565,3 +639,5 @@ Visit the [official PHP documentation](http://www.php.net/manual/) for reference
If you're interested in up-to-date best practices, visit [PHP The Right Way](http://www.phptherightway.com/).
If you're coming from a language with good package management, check out [Composer](http://getcomposer.org/).
+
+For common standards, visit the PHP Framework Interoperability Group's [PSR standards](https://github.com/php-fig/fig-standards).