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PHP / array_reverse — DevDocs

array_reverse

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

array_reverse Return an array with elements in reverse order

Description

array_reverse(array $array, bool $preserve_keys = false): array

Takes an input array and returns a new array with the order of the elements reversed.

Parameters

array

The input array.

preserve_keys

If set to true numeric keys are preserved. Non-numeric keys are not affected by this setting and will always be preserved.

Return Values

Returns the reversed array.

Examples

Example #1 array_reverse() example

<?php
$input  = array("php", 4.0, array("green", "red"));
$reversed = array_reverse($input);
$preserved = array_reverse($input, true);

print_r($input);
print_r($reversed);
print_r($preserved);
?>

The above example will output:

Array
(
    [0] => php
    [1] => 4
    [2] => Array
        (
            [0] => green
            [1] => red
        )

)
Array
(
    [0] => Array
        (
            [0] => green
            [1] => red
        )

    [1] => 4
    [2] => php
)
Array
(
    [2] => Array
        (
            [0] => green
            [1] => red
        )

    [1] => 4
    [0] => php
)

See Also

  • array_flip() - Exchanges all keys with their associated values in an array
PHP / array_search — DevDocs
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PHP / array_shift — DevDocs

array_shift

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

array_shift Shift an element off the beginning of array

Description

array_shift(array &$array): mixed

array_shift() shifts the first value of the array off and returns it, shortening the array by one element and moving everything down. All numerical array keys will be modified to start counting from zero while literal keys won't be affected.

Note : This function will reset() the array pointer of the input array after use.

Parameters

array

The input array.

Return Values

Returns the shifted value, or null if array is empty or is not an array.

Examples

Example #1 array_shift() example

<?php
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_shift($stack);
print_r($stack);
?>

The above example will output:

Array
(
    [0] => banana
    [1] => apple
    [2] => raspberry
)

and orange will be assigned to $fruit .

See Also

  • array_unshift() - Prepend one or more elements to the beginning of an array
  • array_push() - Push one or more elements onto the end of array
  • array_pop() - Pop the element off the end of array
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PHP / array_slice — DevDocs

array_slice

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

array_slice Extract a slice of the array

Description

array_slice(
 array $array,
 int $offset,
 ?int $length = null,
 bool $preserve_keys = false
): array

array_slice() returns the sequence of elements from the array array as specified by the offset and length parameters.

Parameters

array

The input array.

offset

If offset is non-negative, the sequence will start at that offset in the array .

If offset is negative, the sequence will start that far from the end of the array .

Note :

The offset parameter denotes the position in the array, not the key.

length

If length is given and is positive, then the sequence will have up to that many elements in it.

If the array is shorter than the length , then only the available array elements will be present.

If length is given and is negative then the sequence will stop that many elements from the end of the array.

If it is omitted, then the sequence will have everything from offset up until the end of the array .

preserve_keys

Note :

array_slice() will reorder and reset the integer array indices by default. This behaviour can be changed by setting preserve_keys to true . String keys are always preserved, regardless of this parameter.

Return Values

Returns the slice. If the offset is larger than the size of the array, an empty array is returned.

Examples

Example #1 array_slice() examples

<?php
$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"

// note the differences in the array keys
print_r(array_slice($input, 2, -1));
print_r(array_slice($input, 2, -1, true));
?>

The above example will output:

Array
(
    [0] => c
    [1] => d
)
Array
(
    [2] => c
    [3] => d
)

Example #2 array_slice() and one-based array

<?php
$input = array(1 => "a", "b", "c", "d", "e");
print_r(array_slice($input, 1, 2));
?>

The above example will output:

Array
(
    [0] => b
    [1] => c
)

Example #3 array_slice() and array with mixed keys

<?php
$ar = array('a'=>'apple', 'b'=>'banana', '42'=>'pear', 'd'=>'orange');
print_r(array_slice($ar, 0, 3));
print_r(array_slice($ar, 0, 3, true));
?>

The above example will output:

Array
(
    [a] => apple
    [b] => banana
    [0] => pear
)
Array
(
    [a] => apple
    [b] => banana
    [42] => pear
)

See Also

  • array_chunk() - Split an array into chunks
  • array_splice() - Remove a portion of the array and replace it with something else
  • unset() - Unset a given variable
Read article
PHP / array_splice — DevDocs

array_splice

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

array_splice Remove a portion of the array and replace it with something else

Description

array_splice(
 array &$array,
 int $offset,
 ?int $length = null,
 mixed $replacement = []
): array

Removes the elements designated by offset and length from the array array, and replaces them with the elements of the replacement array, if supplied.

Note :

Numerical keys in array are not preserved.

Note : If replacement is not an array, it will be typecast to one (i.e. (array) $replacement ). This may result in unexpected behavior when using an object or null replacement .

Parameters

array

The input array.

offset

If offset is positive then the start of the removed portion is at that offset from the beginning of the array array.

If offset is negative then the start of the removed portion is at that offset from the end of the array array.

length

If length is omitted, removes everything from offset to the end of the array.

If length is specified and is positive, then that many elements will be removed.

If length is specified and is negative, then the end of the removed portion will be that many elements from the end of the array.

If length is specified and is zero, no elements will be removed.

Tip

To remove everything from offset to the end of the array when replacement is also specified, use count($input) for length .

replacement

If replacement array is specified, then the removed elements are replaced with elements from this array.

If offset and length are such that nothing is removed, then the elements from the replacement array are inserted in the place specified by the offset .

Note :

Keys in the replacement array are not preserved.

If replacement is just one element it is not necessary to put array() or square brackets around it, unless the element is an array itself, an object or null .

Return Values

Returns an array consisting of the extracted elements.

Changelog

Version Description
8.0.0 length is nullable now.

Examples

Example #1 array_splice() examples

<?php
$input = array("red", "green", "blue", "yellow");
array_splice($input, 2);
var_dump($input);

$input = array("red", "green", "blue", "yellow");
array_splice($input, 1, -1);
var_dump($input);

$input = array("red", "green", "blue", "yellow");
array_splice($input, 1, count($input), "orange");
var_dump($input);

$input = array("red", "green", "blue", "yellow");
array_splice($input, -1, 1, array("black", "maroon"));
var_dump($input);
?>

The above example will output:

array(2) {
  [0]=>
  string(3) "red"
  [1]=>
  string(5) "green"
}
array(2) {
  [0]=>
  string(3) "red"
  [1]=>
  string(6) "yellow"
}
array(2) {
  [0]=>
  string(3) "red"
  [1]=>
  string(6) "orange"
}
array(5) {
  [0]=>
  string(3) "red"
  [1]=>
  string(5) "green"
  [2]=>
  string(4) "blue"
  [3]=>
  string(5) "black"
  [4]=>
  string(6) "maroon"
}

Example #2 Equivalent statements to various array_splice() examples

The following statements are equivalent:

<?php

// append two elements to $input
array_push($input, $x, $y);
array_splice($input, count($input), 0, array($x, $y));

// remove the last element of $input
array_pop($input);
array_splice($input, -1);

// remove the first element of $input
array_shift($input);
array_splice($input, 0, 1);

// insert an element at the start of $input
array_unshift($input, $x, $y);
array_splice($input, 0, 0, array($x, $y));

// replace the value in $input at index $x
$input[$x] = $y; // for arrays where key equals offset
array_splice($input, $x, 1, $y);

?>

See Also

  • array_merge() - Merge one or more arrays
  • array_slice() - Extract a slice of the array
  • unset() - Unset a given variable
Read article
PHP / array_sum — DevDocs

array_sum

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

array_sum Calculate the sum of values in an array

Description

array_sum(array $array): int|float

array_sum() returns the sum of values in an array.

Parameters

array

The input array.

Return Values

Returns the sum of values as an integer or float; 0 if the array is empty.

Examples

Example #1 array_sum() examples

<?php
$a = array(2, 4, 6, 8);
echo "sum(a) = " . array_sum($a) . "\n";

$b = array("a" => 1.2, "b" => 2.3, "c" => 3.4);
echo "sum(b) = " . array_sum($b) . "\n";
?>

The above example will output:

sum(a) = 20
sum(b) = 6.9
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