Takes an input
array
and returns a new array without duplicate values.
Note that keys are preserved. If multiple elements compare equal under the given
flags
, then the key and value of the first equal element will be retained.
Note
:
Two elements are considered equal if and only if
(string) $elem1 === (string) $elem2
i.e. when the string representation is the same, the first element will be used.
Parameters
array
The input array.
flags
The optional second parameter
flags
may be used to modify the sorting behavior using these values:
SORT_LOCALE_STRING
- compare items as strings, based on the current locale.
Return Values
Returns the filtered array.
Changelog
Version
Description
7.2.0
If
flags
is
SORT_STRING
, formerly
array
has been copied and non-unique elements have been removed (without packing the array afterwards), but now a new array is built by adding the unique elements. This can result in different numeric indexes.
Note
:
Note that
array_unique()
is not intended to work on multi dimensional arrays.
See Also
array_count_values() - Counts all the values of an array
PHP / array_unshift — DevDocs
array_unshift
(PHP 4, PHP 5, PHP 7, PHP 8)
array_unshift
—
Prepend one or more elements to the beginning of an array
Description
array_unshift(array&$array,mixed...$values):int
array_unshift()
prepends passed elements to the front of the
array
. Note that the list of elements is prepended as a whole, so that the prepended elements stay in the same order. All numerical array keys will be modified to start counting from zero while literal keys won't be changed.
Note
:
Resets array's internal pointer to the first element.
Parameters
array
The input array.
values
The values to prepend.
Return Values
Returns the new number of elements in the
array
.
Changelog
Version
Description
7.3.0
This function can now be called with only one parameter. Formerly, at least two parameters have been required.
Applies the user-defined
callback
function to each element of the
array
array.
array_walk()
is not affected by the internal array pointer of
array
.
array_walk()
will walk through the entire array regardless of pointer position.
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.
Note
:
Many internal functions (for example
strtolower()
) will throw a warning if more than the expected number of argument are passed in and are not usable directly as a
callback
.
Only the values of the
array
may potentially be changed; its structure cannot be altered, i.e., the programmer cannot add, unset or reorder elements. If the callback does not respect this requirement, the behavior of this function is undefined, and unpredictable.
arg
If the optional
arg
parameter is supplied, it will be passed as the third parameter to the
callback
.
Return Values
Returns
true
.
Errors/Exceptions
As of PHP 7.1.0, an
ArgumentCountError
will be thrown if the
callback
function requires more than 2 parameters (the value and key of the array member), or more than 3 parameters if the
arg
is also passed. Previously, in this case an error of level E_WARNING would be generated each time
array_walk()
calls
callback
.
Changelog
Version
Description
8.0.0
If
callback
expects the second or third parameter to be passed by reference, this function will now emit an
E_WARNING
.
Examples
Example #1
array_walk()
example
<?php$fruits=array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple");functiontest_alter(&$item1,$key,$prefix){$item1="$prefix: $item1";}functiontest_print($item2,$key){echo"$key. $item2\n";}echo"Before ...:\n";array_walk($fruits,'test_print');array_walk($fruits,'test_alter','fruit');echo"... and after:\n";array_walk($fruits,'test_print');?>
The above example will output:
Before ...:
d. lemon
a. orange
b. banana
c. apple
... and after:
d. fruit: lemon
a. fruit: orange
b. fruit: banana
c. fruit: apple
Example #2
array_walk()
example using anonymous function
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
.