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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 ?>
```
@ -108,21 +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();