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PHP / array_walk_recursive — DevDocs

array_walk_recursive

(PHP 5, PHP 7, PHP 8)

array_walk_recursive Apply a user function recursively to every member of an array

Description

array_walk_recursive(array|object &$array, callable $callback, mixed $arg = null): bool

Applies the user-defined callback function to each element of the array . This function will recurse into deeper arrays.

Parameters

array

The input array.

callback

Typically, callback takes on two parameters. The array parameter's value being the first, and the key/index second.

Note :

If callback needs to be working with the actual values of the array, specify the first parameter of callback as a reference. Then, any changes made to those elements will be made in the original array itself.

arg

If the optional arg parameter is supplied, it will be passed as the third parameter to the callback .

Return Values

Returns true on success or false on failure.

Examples

Example #1 array_walk_recursive() example

<?php
$sweet = array('a' => 'apple', 'b' => 'banana');
$fruits = array('sweet' => $sweet, 'sour' => 'lemon');

function test_print($item, $key)
{
    echo "$key holds $item\n";
}

array_walk_recursive($fruits, 'test_print');
?>

The above example will output:

a holds apple
b holds banana
sour holds lemon

You may notice that the key ' sweet ' is never displayed. Any key that holds an array will not be passed to the function.

See Also

  • array_walk() - Apply a user supplied function to every member of an array
PHP / arsort — DevDocs

arsort

(PHP 4, PHP 5, PHP 7, PHP 8)

arsort Sort an array in descending order and maintain index association

Description

arsort(array &$array, int $flags = SORT_REGULAR): bool

Sorts array in place in descending order, such that its keys maintain their correlation with the values they are associated with.

This is used mainly when sorting associative arrays where the actual element order is significant.

Note :

If two members compare as equal, they retain their original order. Prior to PHP 8.0.0, their relative order in the sorted array was undefined.

Note :

Resets array's internal pointer to the first element.

Parameters

array

The input array.

flags

The optional second parameter flags may be used to modify the sorting behavior using these values:

Sorting type flags:

  • SORT_REGULAR - compare items normally; the details are described in the comparison operators section
  • SORT_NUMERIC - compare items numerically
  • SORT_STRING - compare items as strings
  • SORT_LOCALE_STRING - compare items as strings, based on the current locale. It uses the locale, which can be changed using setlocale()
  • SORT_NATURAL - compare items as strings using "natural ordering" like natsort()
  • SORT_FLAG_CASE - can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively

Return Values

Always returns true .

Examples

Example #1 arsort() example

<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
arsort($fruits);
foreach ($fruits as $key => $val) {
    echo "$key = $val\n";
}
?>

The above example will output:

a = orange
d = lemon
b = banana
c = apple

The fruits have been sorted in reverse alphabetical order, and the index associated with each element has been maintained.

See Also

  • sort() - Sort an array in ascending order
  • asort() - Sort an array in ascending order and maintain index association
  • The comparison of array sorting functions
Read article
PHP / asort — DevDocs

asort

(PHP 4, PHP 5, PHP 7, PHP 8)

asort Sort an array in ascending order and maintain index association

Description

asort(array &$array, int $flags = SORT_REGULAR): bool

Sorts array in place in ascending order, such that its keys maintain their correlation with the values they are associated with.

This is used mainly when sorting associative arrays where the actual element order is significant.

Note :

If two members compare as equal, they retain their original order. Prior to PHP 8.0.0, their relative order in the sorted array was undefined.

Note :

Resets array's internal pointer to the first element.

Parameters

array

The input array.

flags

The optional second parameter flags may be used to modify the sorting behavior using these values:

Sorting type flags:

  • SORT_REGULAR - compare items normally; the details are described in the comparison operators section
  • SORT_NUMERIC - compare items numerically
  • SORT_STRING - compare items as strings
  • SORT_LOCALE_STRING - compare items as strings, based on the current locale. It uses the locale, which can be changed using setlocale()
  • SORT_NATURAL - compare items as strings using "natural ordering" like natsort()
  • SORT_FLAG_CASE - can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively

Return Values

Always returns true .

Examples

Example #1 asort() example

<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
asort($fruits);
foreach ($fruits as $key => $val) {
    echo "$key = $val\n";
}
?>

The above example will output:

c = apple
b = banana
d = lemon
a = orange

The fruits have been sorted in alphabetical order, and the index associated with each element has been maintained.

See Also

  • sort() - Sort an array in ascending order
  • arsort() - Sort an array in descending order and maintain index association
  • The comparison of array sorting functions
Read article
PHP / compact — DevDocs

compact

(PHP 4, PHP 5, PHP 7, PHP 8)

compact Create array containing variables and their values

Description

compact(array|string $var_name, array|string ...$var_names): array

Creates an array containing variables and their values.

For each of these, compact() looks for a variable with that name in the current symbol table and adds it to the output array such that the variable name becomes the key and the contents of the variable become the value for that key. In short, it does the opposite of extract() .

Note :

Before PHP 7.3, any strings that are not set will silently be skipped.

Parameters

var_name
var_names

compact() takes a variable number of parameters. Each parameter can be either a string containing the name of the variable, or an array of variable names. The array can contain other arrays of variable names inside it; compact() handles it recursively.

Return Values

Returns the output array with all the variables added to it.

Errors/Exceptions

compact() issues an E_NOTICE level error if a given string refers to an unset variable.

Changelog

Version Description
7.3.0 compact() now issues an E_NOTICE level error if a given string refers to an unset variable. Formerly, such strings have been silently skipped.

Examples

Example #1 compact() example

<?php
$city  = "San Francisco";
$state = "CA";
$event = "SIGGRAPH";

$location_vars = array("city", "state");

$result = compact("event", $location_vars);
print_r($result);
?>

The above example will output:

Array
(
    [event] => SIGGRAPH
    [city] => San Francisco
    [state] => CA
)

Notes

Note : Gotcha

Because variable variables may not be used with PHP's Superglobal arrays within functions, the Superglobal arrays may not be passed into compact() .

See Also

  • extract() - Import variables into the current symbol table from an array
Read article
PHP / count — DevDocs

count

(PHP 4, PHP 5, PHP 7, PHP 8)

count Counts all elements in an array or in a Countable object

Description

count(Countable|array $value, int $mode = COUNT_NORMAL): int

Counts all elements in an array when used with an array. When used with an object that implements the Countable interface, it returns the return value of the method Countable::count() .

Parameters

value

An array or Countable object.

mode

If the optional mode parameter is set to COUNT_RECURSIVE (or 1), count() will recursively count the array. This is particularly useful for counting all the elements of a multidimensional array.

Caution

count() can detect recursion to avoid an infinite loop, but will emit an E_WARNING every time it does (in case the array contains itself more than once) and return a count higher than may be expected.

Return Values

Returns the number of elements in value . Prior to PHP 8.0.0, if the parameter was neither an array nor an object that implements the Countable interface, 1 would be returned, unless value was null , in which case 0 would be returned.

Changelog

Version Description
8.0.0 count() will now throw TypeError on invalid countable types passed to the value parameter.
7.2.0 count() will now yield a warning on invalid countable types passed to the value parameter.

Examples

Example #1 count() example

<?php
$a[0] = 1;
$a[1] = 3;
$a[2] = 5;
var_dump(count($a));

$b[0]  = 7;
$b[5]  = 9;
$b[10] = 11;
var_dump(count($b));
?>

The above example will output:

int(3)
int(3)

Example #2 count() non Countable|array example (bad example - don't do this)

<?php
$b[0]  = 7;
$b[5]  = 9;
$b[10] = 11;
var_dump(count($b));

var_dump(count(null));

var_dump(count(false));
?>

The above example will output:

int(3)
int(0)
int(1)

Output of the above example in PHP 7.2:

int(3)

Warning: count(): Parameter must be an array or an object that implements Countable in … on line 12
int(0)

Warning: count(): Parameter must be an array or an object that implements Countable in … on line 14
int(1)

Output of the above example in PHP 8:

int(3)

Fatal error: Uncaught TypeError: count(): Argument #1 ($var) must be of type Countable .. on line 12

Example #3 Recursive count() example

<?php
$food = array('fruits' => array('orange', 'banana', 'apple'),
              'veggie' => array('carrot', 'collard', 'pea'));

// recursive count
var_dump(count($food, COUNT_RECURSIVE));

// normal count
var_dump(count($food));

?>

The above example will output:

int(8)
int(2)

Example #4 Countable object

<?php
class CountOfMethods implements Countable
{
    private function someMethod()
    {
    }

    public function count(): int
    {
        return count(get_class_methods($this));
    }
}

$obj = new CountOfMethods();
var_dump(count($obj));
?>

The above example will output:

int(2)

See Also

  • is_array() - Finds whether a variable is an array
  • isset() - Determine if a variable is declared and is different than null
  • empty() - Determine whether a variable is empty
  • strlen() - Get string length
  • is_countable() - Verify that the contents of a variable is a countable value
  • Arrays
Read article
PHP / current — DevDocs

current

(PHP 4, PHP 5, PHP 7, PHP 8)

current Return the current element in an array

Description

current(array|object $array): mixed

Every array has an internal pointer to its "current" element, which is initialized to the first element inserted into the array.

Parameters

array

The array.

Return Values

The current() function simply returns the value of the array element that's currently being pointed to by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, current() returns false .

Warning

This function may return Boolean false , but may also return a non-Boolean value which evaluates to false . Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

Changelog

Version Description
8.1.0 Calling this function on object s is deprecated. Either use get_mangled_object_vars() on the object first, or use ArrayIterator .

Examples

Example #1 Example use of current() and friends

<?php
$transport = array('foot', 'bike', 'car', 'plane');
$mode = current($transport); // $mode = 'foot';
$mode = next($transport);    // $mode = 'bike';
$mode = current($transport); // $mode = 'bike';
$mode = prev($transport);    // $mode = 'foot';
$mode = end($transport);     // $mode = 'plane';
$mode = current($transport); // $mode = 'plane';

$arr = array();
var_dump(current($arr)); // bool(false)

$arr = array(array());
var_dump(current($arr)); // array(0) { }
?>

Notes

Note : The results of calling current() on an empty array and on an array, whose internal pointer points beyond the end of the elements, are indistinguishable from a bool false element. To properly traverse an array which may contain false elements, see the foreach control structure. To still use current() and properly check if the value is really an element of the array, the key() of the current() element should be checked to be strictly different from null .

See Also

  • end() - Set the internal pointer of an array to its last element
  • key() - Fetch a key from an array
  • each() - Return the current key and value pair from an array and advance the array cursor
  • prev() - Rewind the internal array pointer
  • reset() - Set the internal pointer of an array to its first element
  • next() - Advance the internal pointer of an array
  • foreach
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