PHP

Archived

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Misc

REPL

php -a

Naming Conventions

See: http://php.net/manual/en/userlandnaming.rules.php

  • Similar to Python naming conventions
    • Function names should be lowercase, with words separated by underscores
    • Class names use the CapWords convention
    • Method names use camelCase
    • Constants are written in all capital letters with underscores separating words
    • Use lowercase true, false, and null: 
      return true;

Arrays

PHP arrays all act the same, whether or not they’re “associative” or “numerically indexed.” If it’s associative, adding a new element (with no key), will take the last used integer and add 1 for the key (or 0 if no previously used integer as a key.

Parse all the elements of an array:

foreach ($array as $value) {
    function($value);
}


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

}

print_r($array);

or:

var_dump($array);

or:

$var = var_export($array, true);
echo $var;

Create a simple array

$array = array($something, $something else, 2, 'blue');

Add elements to a numerically indexed array

$array = array();
$array[] = 'first value';
$array[] = 'second value';

Check for a value in an array

if (in_array($value, $array))

Check for a key in an array

if (array_key_exists($key, $array))

Remove a key (and all its values) from an array

unset($array[$key]);

Get the number of elements in an array

count($array);

Get a chunk of an array

$input = array("a", "b", "c", "d", "e");

$output = array_slice($input, 2);      // returns "c", "d", and "e"
$output = array_slice($input, -2, 1);  // returns "d"
$output = array_slice($input, 0, 3);   // returns "a", "b", and "c"

print_r(array_slice($input, 2, -1));    // Array([0] => c [1] => d)
print_r(array_slice($input, 2, -1, true));    // Array([2] => c [3] => d)

Get the last value of an array

end(array_values($array));

Add one array to another

$new_array = array_merge($array1, $array2);

Strings

Define a string

(do this if you want to concatenate later and it isn’t defined)

$string = '';

Concatenate a string

$string .= $something_else;

Check for a value in a string

strstr($string, $value);

Returns the portion of string, or FALSE if value is not found.

Replace a value in a string

$newstring = str_replace($oldsubstring, $newsubstring, $string);

Split (explode) a string into an array

explode($delimiter, $string [, $limit]);

Ex:

explode(',', 'this,that');

Strip whitespace

trim($string);

echo "myvar={$myvar}<br />\n";

printf('There is a difference between %s and %s', 'good', 'evil');

Return a formatted string

$mystring = sprintf('There is a difference between %s and %s', 'good', 'evil');

Multi-line string

echo "First line<br />\n" .
     "Second line<br />\n";

Compare two strings

if ($string1 === 'test') {

Warning: don’t use == !!!

Loops

Go to the next element in a loop

continue;

Functions

Define a function

function my_function() {
}

Return a value from a function

return $value;

Check for the existence of a function

if (function_exists('my_function')) {
}

Default argument values

function my_function($myval1 = 1, $myval2 = null) {
}

*All of the arguments with default values then become optional. for example, this function can now be called with no arguments

Mysql

Use mysqli

OOP

Calling class methods

use :: for static methods, and -> for instance methods

Ex:

Class::method();
$instance->method();

Accessing object properties/variables

Use ->:

$object->property;

Exceptions

try {
    $ccache->initPassword('user@EXAMPLE.ORG', 'password');
} catch (Exception $e) {
    echo($e->getMessage() . "<br />\n");
    echo($e->getCode() . "<br />\n");
}

Misc

Comparing to true

Use === true if you want to match true itself (and not strings, or any other non-zero/false value):

echo "test" == true;
1
echo "test" === true;

(returns nothing)

Evaluation of variables

if ($variable) {
    variable is defined and anything but 0 or '0'
} else {
    variable isn't defined (or is null, see below)
    variable is defined but empty ($variable = '';)
    variable is set to 0 ($variable = '0'; or $variable = 0;)
}

Null variables

A variable is null if:

  1. It hasn’t been defined yet
  2. It’s been assigned the null value 
    $myvar = null;  // (null is case-insensitive)
  3. It’s been unset using the unset() function

Check if a variable or an array is empty

empty($var)

or

empty($array)

If statements

if ($somevar) {
    do_something();
} elseif ($someothervar) {
    do_something_else();
} else {
    ...
}

Get the value of a global PHP setting

echo ini_get('memory_limit');

End the current script

exit();

or

exit;

or

exit(STATUS MESSAGE OR CODE);

Filesystem evaluation

dir

  • is_file:
  • is_dir: 1
  • is_link:

file

  • is_file: 1
  • is_dir:
  • is_link:

link

  • is_file: 1
  • is_dir:
  • is_link: 1

Access POST variables

$somevar = $_POST['myvar'];

Logging

use error_log:

error_log('ERROR: log some stuff');