PHP basics

This tutorial will show you basic PHP syntax and its features. If you’re new to PHP read the most basic PHP tutorial to get started as quickly and painlessly as possible. For becoming modern PHP developer read and follow also PHP: The Right Way. Seriously.

PHP in a nutshell

scripting language
procedural and object oriented language
dynamically (weakly) typed
syntax similar to C, C++, C#, Java and Perl
Imperative language
PHP has closures

Basic syntax

Hello world

File hello.php:



echo 'Hello, world.';

$ php hello.php

Operators

Arithmetic operators

Operator	Name	Result
`-$a`	negation	Opposite of $a.
`$a + $b`	addition	Sum of $a and $b.
`$a - $b`	Subtraction	Difference of $a and $b.
`$a * $b`	Multiplication	Product of $a and $b.
`$a / $b`	division	Quotient of $a and $b.
`$a % $b`	modulus	Remainder of $a divided by $b.
`$a ** $b`	Exponentiation	Result of raising $a to the $b’th power.

Comparison operators

Operator	Name	Result
`$a == $b`	Equal	TRUE if $a is equal to $b after type juggling.
`$a === $b`	Identical	TRUE if $a is equal to $b, and they are of the same type.
`$a != $b`	Not equal	TRUE if $a is not equal to $b after type juggling.
`$a <> $b`	Not equal	TRUE if $a is not equal to $b after type juggling.
`$a !== $b`	Not identical	TRUE if $a is not equal to $b, or they are not of the same type.
`$a < $b`	Less than	TRUE if $a is strictly less than $b.
`$a > $b`	Greater than	TRUE if $a is strictly greater than $b.
`$a <= $b`	Less than or equal to	TRUE if $a is less than or equal to $b.
`$a >= $b`	Greater than or equal to	TRUE if $a is greater than or equal to $b.

Logical operators

Operator	Name	Result
`$a and $b`	And	TRUE if both $a and $b are TRUE.
`$a or $b`	Or	TRUE if either $a or $b is TRUE.
`$a xor $b`	Xor	TRUE if either $a or $b is TRUE, but not both.
`! $a`	Not	TRUE if $a is not TRUE.
`$a && $b`	And	TRUE if both $a and $b are TRUE.
`$a \|\| $b`	Or	TRUE if either $a or $b is TRUE.

Assignment operators

Operator	Description
`=`	Set a value to variable
`+=`	Addition of numeric value to variable
`.=`	Add string to variable

Declarations

$i = 1; - assign value to variable
define('FOO', 'something'); - define a constant *

Functions

// a simple function
function functionName() {}

// function with parameters
function functionName($param1, $param2) {}

Anonymous functions (closures)


echo preg_replace_callback('~-([a-z])~', function ($match) {
    return strtoupper($match[1]);
}, 'hello-world');
// outputs helloWorld

// Anonymous function variable assignment example
$greet = function($name) {
    printf("Hello %s\r\n", $name);
};
$greet('World');

// inherit
$message = 'hello';

// Without "use" keyword
$example = function () {
    var_dump($message);
};
echo $example();

// Inherit $message
$example = function () use ($message) {
    var_dump($message);
};
echo $example();

Variadic functions


function sum(...$nums)
{
    return array_sum($nums);
}

Control structures

If

if $x > 0 {
    return $x;
} else {
    return -$x;
}

Loops

// for
for ($i = 1; $i<10 span="">; $i++) {}

// while
while ($i < 10) {}

// do while
$i = 0;
do {
    echo $i;
} while ($i > 0);


// foreach
foreach ($array as $key => $value) {}

Switch

// switch statement
switch ($operatingSystem) {
    case 'darwin':
        echo 'Mac OS Hipster';
        break;
    case 'linux':
        echo 'Linux Geek';
        break;
    default:
        // Windows, BSD, ...
        echo 'Other';
}

Arrays

$array = [
    "foo" => "bar",
    "bar" => "foo",
];

Operations on arrays

Operator	Name	Result
`$a + $b`	Union	Union of $a and $b.
`$a == $b`	Equality	TRUE if $a and $b have the same key/value pairs.
`$a === $b`	Identity	TRUE if $a and $b have the same key/value pairs in the same order and of the same types.
`$a != $b`	Inequality	TRUE if $a is not equal to $b.
`$a <> $b`	Inequality	TRUE if $a is not equal to $b.
`$a !== $b`	Non-identity	TRUE if $a is not identical to $b.

Built-in types

Type
boolean
integer
float
string
array
object
resource
NULL

Errors

PHP errors


// Turn off all error reporting
error_reporting(0);

// Report simple running errors
error_reporting(E_ERROR | E_WARNING | E_PARSE);

// Reporting E_NOTICE can be good too (to report uninitialized
// variables or catch variable name misspellings ...)
error_reporting(E_ERROR | E_WARNING | E_PARSE | E_NOTICE);

// Report all errors except E_NOTICE
error_reporting(E_ALL & ~E_NOTICE);

// Report all PHP errors (see changelog)
error_reporting(E_ALL);

// Report all PHP errors
error_reporting(-1);

// Same as error_reporting(E_ALL);
ini_set('error_reporting', E_ALL);

Exceptions

function inverse($x) {
    if (!$x) {
        throw new Exception('Division by zero.');
    }
    return 1/$x;
}

try {
    echo inverse(5) . "\n";
} catch (Exception $e) {
    echo 'Caught exception: ',  $e->getMessage(), "\n";
} finally {
    echo "This is always executed.\n";
}

What is next?

Use php.net. It has a great and detailed manual for a lot of your PHP adventures.

Advanced php tutorials

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