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Fix up PHP

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Adam 2013-06-27 09:49:03 -07:00
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@ -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
$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
$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 $${integer} in the bank." // Enclose a variable in curly braces if needed
// Strings should be enclosed in single quotes;
$sgl_quotes = '$String'; // => '$String'
// Avoid using double quotes except to embed other variables
$dbl_quotes = "This is a $sgl_quotes." // => 'This is a $String'
// Escape special characters with backslash
$escaped = "This contains a \t tab character.";
// Enclose a variable in curly braces if needed
$money = "I have $${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 ?>
```
@ -108,15 +133,21 @@ 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.
@ -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
```
@ -158,6 +194,8 @@ $var = null; // Null value
### If Statements
```php
<?php
if (/* test */) {
// Do something
}
@ -181,6 +219,7 @@ if (/* test */) {
} else {
// Do something default
}
?>
<?php if (/* test */): ?>
<!-- Do something that isn't PHP -->
@ -192,6 +231,8 @@ if (/* test */) {
### Switch statements
```php
<?php
switch ($variable) {
case 'one':
// Do something if $variable == 'one'
@ -209,6 +250,8 @@ switch ($variable) {
### Loops
```php
<?php
$i = 0;
while ($i < 5) {
echo $i++;
@ -255,6 +298,8 @@ while ($i < 5) {
Functions are created with the ```function``` keyword.
```php
<?php
function my_function($my_arg) {
$my_variable = 1;
}
@ -265,16 +310,21 @@ function my_function($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 $arg_2;
}
@ -291,6 +341,8 @@ function outer_function ($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
@ -301,6 +353,8 @@ $function_name(); // will execute the my_function_name() function
Similar to variable functions, functions may be anonymous.
```php
<?php
my_function(function () {
// do something
});
@ -318,6 +372,8 @@ $my_function();
Classes are defined with the ```class``` keyword.
```php
<?php
class MyClass {
const MY_CONST = 'value';
static $staticVar = 'something';
@ -330,9 +386,12 @@ 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() {
}
@ -358,6 +417,8 @@ 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;
@ -373,13 +434,15 @@ class MyClass {
}
$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();
@ -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;
@ -447,6 +518,8 @@ $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()
{