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-rw-r--r--php.html.markdown162
1 files changed, 146 insertions, 16 deletions
diff --git a/php.html.markdown b/php.html.markdown
index 039288a0..0504ced2 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.
@@ -60,7 +60,7 @@ $float = 1.2e3;
$float = 7E-10;
// Delete variable
-unset($int1)
+unset($int1);
// Arithmetic
$sum = 1 + 1; // 2
@@ -103,6 +103,9 @@ 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
@@ -115,8 +118,10 @@ echo 'This string ' . 'is concatenated';
// followed by any number of letters, numbers, or underscores.
define("FOO", "something");
-// access to a constant is possible by direct using the choosen name
-echo 'This outputs '.FOO;
+// 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'
+
/********************************
@@ -141,6 +146,8 @@ 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 +162,9 @@ 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!';
$paragraph = 'paragraph';
@@ -215,6 +222,18 @@ assert($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.
$integer = 1;
@@ -264,6 +283,18 @@ if (false) {
// ternary operator
print (false ? 'Does not get printed' : 'Does');
+// ternary shortcut operator since PHP 5.3
+// equivalent of "$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';
@@ -359,7 +390,7 @@ for ($i = 0; $i < 5; $i++) {
// Define a function with "function":
function my_function () {
- return 'Hello';
+ return 'Hello';
}
echo my_function(); // => "Hello"
@@ -368,8 +399,8 @@ echo my_function(); // => "Hello"
// number of letters, numbers, or underscores.
function add ($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 +411,21 @@ 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 +437,31 @@ 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 $item . ' | ';
+ }
+}
+
+variable("Separate", "Hello", "World") // Separate || Hello | World |
+
/********************************
* Includes
*/
@@ -487,7 +543,7 @@ class MyClass
* Declaring class properties or methods as static makes them accessible without
* needing an instantiation of the class. A property declared as static can not
* be accessed with an instantiated class object (though a static method can).
-*/
+ */
public static function myStaticMethod()
{
@@ -495,7 +551,9 @@ class MyClass
}
}
+// Class constants can always be accessed statically
echo MyClass::MY_CONST; // Outputs 'value';
+
echo MyClass::$staticVar; // Outputs 'static';
MyClass::myStaticMethod(); // Outputs 'I am static';
@@ -671,8 +729,80 @@ 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
+*/
+
+
+/**********************
+* 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
+}
+
```
## More Information