删除空数组元素

Question

Some elements in my array are empty strings based on what the user has submitted. I need to remove those elements. I have this:

foreach($linksArray as $link)
{
    if($link == '')
    {
        unset($link);
    }
}
print_r($linksArray);

But it doesn't work. $linksArray still has empty elements. I have also tried doing it with the empty() function, but the outcome is the same.

Answer 1

As you're dealing with an array of strings, you can simply use array_filter() , which conveniently handles all this for you:

print_r(array_filter($linksArray));

Keep in mind that if no callback is supplied , all entries of array equal to FALSE (see converting to boolean ) will be removed. So if you need to preserve elements that are ie exact string '0' , you will need a custom callback:

// PHP 7.4 and later
print_r(array_filter($linksArray, fn($value) => !is_null($value) && $value !== ''));

// PHP 5.3 and later
print_r(array_filter($linksArray, function($value) { return !is_null($value) && $value !== ''; }));

// PHP < 5.3
print_r(array_filter($linksArray, create_function('$value', 'return $value !== "";')));

Answer 2

You can use array_filter to remove empty elements:

$emptyRemoved = array_filter($linksArray);

If you have (int) 0 in your array, you may use the following:

$emptyRemoved = remove_empty($linksArray);

function remove_empty($array) {
  return array_filter($array, '_remove_empty_internal');
}

function _remove_empty_internal($value) {
  return !empty($value) || $value === 0;
}

EDIT: Maybe your elements are not empty per se but contain one or more spaces... You can use the following before using array_filter

$trimmedArray = array_map('trim', $linksArray);

Answer 3

The most popular answer on this topic is absolutely INCORRECT.

Consider the following PHP script:

<?php
$arr = array('1', '', '2', '3', '0');
// Incorrect:
print_r(array_filter($arr));
// Correct:
print_r(array_filter($arr, 'strlen'));

Why is this? Because a string containing a single '0' character also evaluates to boolean false, so even though it's not an empty string, it will still get filtered. That would be a bug.

Passing the built-in strlen function as the filtering function will work, because it returns a non-zero integer for a non-empty string, and a zero integer for an empty string. Non-zero integers always evaluate to true when converted to boolean, while zero integers always evaluate to false when converted to boolean.

So, the absolute, definitive, correct answer is:

$arr = array_filter($arr, 'strlen');

Answer 4

$linksArray = array_filter($linksArray);

"If no callback is supplied, all entries of input equal to FALSE will be removed." -- http://php.net/manual/en/function.array-filter.php

Answer 5

    $myarray = array_filter($myarray, 'strlen');  //removes null values but leaves "0"
    $myarray = array_filter($myarray);            //removes all null values

Answer 6

You can just do

array_filter($array)

array_filter: "If no callback is supplied, all entries of input equal to FALSE will be removed." This means that elements with values NULL, 0, '0', '', FALSE, array() will be removed too.

The other option is doing

array_diff($array, array(''))

which will remove elements with values NULL, '' and FALSE.

Hope this helps :)

UPDATE

Here is an example.

$a = array(0, '0', NULL, FALSE, '', array());

var_dump(array_filter($a));
// array()

var_dump(array_diff($a, array(0))) // 0 / '0'
// array(NULL, FALSE, '', array());

var_dump(array_diff($a, array(NULL))) // NULL / FALSE / ''
// array(0, '0', array())

To sum up:

• 0 or '0' will remove 0 and '0'
• NULL, FALSE or '' will remove NULL, FALSE and ''

Answer 7

foreach($linksArray as $key => $link) 
{ 
    if($link === '') 
    { 
        unset($linksArray[$key]); 
    } 
} 
print_r($linksArray); 

Answer 8

Another one liner to remove empty ("" empty string) elements from your array.

$array = array_filter($array, function($a) {return $a !== "";});

Note: This code deliberately keeps null , 0 and false elements.

---

Or maybe you want to trim your array elements first:

$array = array_filter($array, function($a) {
    return trim($a) !== "";
});

Note: This code also removes null and false elements.

Answer 9

In short:

This is my suggested code:

$myarray =  array_values(array_filter(array_map('trim', $myarray), 'strlen'));

Explanation:

I thinks use array_filter is good, but not enough, because values be like space and \\n ,... keep in the array and this is usually bad.

So I suggest you use mixture ‍‍ array_filter and array_map .

array_map is for trimming, array_filter is for remove empty values, strlen is for keep 0 value, and array_values is for re indexing if you needed.

Samples:

$myarray = array("\r", "\n", "\r\n", "", " ", "0", "a");

// "\r", "\n", "\r\n", " ", "a"
$new1 = array_filter($myarray);

// "a"
$new2 = array_filter(array_map('trim', $myarray));

// "0", "a"
$new3 = array_filter(array_map('trim', $myarray), 'strlen');

// "0", "a" (reindex)
$new4 = array_values(array_filter(array_map('trim', $myarray), 'strlen'));

var_dump($new1, $new2, $new3, $new4);

Results:

array(5) {
  [0]=>
" string(1) "
  [1]=>
  string(1) "
"
  [2]=>
  string(2) "
"
  [4]=>
  string(1) " "
  [6]=>
  string(1) "a"
}
array(1) {
  [6]=>
  string(1) "a"
}
array(2) {
  [5]=>
  string(1) "0"
  [6]=>
  string(1) "a"
}
array(2) {
  [0]=>
  string(1) "0"
  [1]=>
  string(1) "a"
}

Online Test:

http://sandbox.onlinephpfunctions.com/code/e02f5d8795938be9f0fa6f4c17245a9bf8777404

Answer 10

If you are working with a numerical array and need to re-index the array after removing empty elements, use the array_values function:

array_values(array_filter($array));

Also see: PHP reindex array?

Answer 11

The most voted answer is wrong or at least not completely true as the OP is talking about blank strings only. Here's a thorough explanation:

What does empty mean?

First of all, we must agree on what empty means. Do you mean to filter out:

1. the empty strings only ("")?
2. the strictly false values? ( $element === false )
3. the falsey values? (ie 0, 0.0, "", "0", NULL, array()...)
4. the equivalent of PHP's empty() function?

How do you filter out the values

To filter out empty strings only :

$filtered = array_diff($originalArray, array(""));

To only filter out strictly false values, you must use a callback function:

$filtered = array_diff($originalArray, 'myCallback');
function myCallback($var) {
    return $var === false;
}

The callback is also useful for any combination in which you want to filter out the "falsey" values, except some. (For example, filter every null and false , etc, leaving only 0 ):

$filtered = array_filter($originalArray, 'myCallback');
function myCallback($var) {
    return ($var === 0 || $var === '0');
}

Third and fourth case are (for our purposes at last) equivalent, and for that all you have to use is the default:

$filtered = array_filter($originalArray);

Answer 12

I had to do this in order to keep an array value of (string) 0

$url = array_filter($data, function ($value) {
  return (!empty($value) || $value === 0 || $value==='0');
});

Answer 13

$a = array(1, '', '', '', 2, '', 3, 4);
$b = array_values(array_filter($a));

print_r($b)

Answer 14

For multidimensional array

$data = array_map('array_filter', $data);
$data = array_filter($data);

Answer 15

function trim_array($Array)
{
    foreach ($Array as $value) {
        if(trim($value) === '') {
            $index = array_search($value, $Array);
            unset($Array[$index]);
        }
    }
    return $Array;
}

Answer 16

$out_array = array_filter($input_array, function($item) 
{ 
    return !empty($item['key_of_array_to_check_whether_it_is_empty']); 
}
);

Answer 17

I use the following script to remove empty elements from an array

for ($i=0; $i<$count($Array); $i++)
  {
    if (empty($Array[$i])) unset($Array[$i]);
  }

Answer 18

Just want to contribute an alternative to loops...also addressing gaps in keys...

In my case I wanted to keep sequential array keys when the operation was complete (not just odd numbers, which is what I was staring at. Setting up code to look just for odd keys seemed fragile to me and not future-friendly.)

I was looking for something more like this: http://gotofritz.net/blog/howto/removing-empty-array-elements-php/

The combination of array_filter and array_slice does the trick.

$example = array_filter($example); $example = array_slice($example,0);

No idea on efficiencies or benchmarks but it works.

Answer 19

只有一行：更新（感谢@suther）：

$array_without_empty_values = array_filter($array);

Answer 20

$my = ("0"=>" ","1"=>"5","2"=>"6","3"=>" ");   

foreach ($my as $key => $value) {
    if (is_null($value)) unset($my[$key]);
}

foreach ($my as $key => $value) {
    echo   $key . ':' . $value . '<br>';
} 

output

1:5

2:6

Answer 21

foreach($arr as $key => $val){
   if (empty($val)) unset($arr[$key];
}

Answer 22

use array_filter function to remove empty values:

$linksArray = array_filter($linksArray);
print_r($linksArray);

Answer 23

Remove empty array elements

function removeEmptyElements(&$element)
{
    if (is_array($element)) {
        if ($key = key($element)) {
            $element[$key] = array_filter($element);
        }

        if (count($element) != count($element, COUNT_RECURSIVE)) {
            $element = array_filter(current($element), __FUNCTION__);
        }

        return $element;
    } else {
        return empty($element) ? false : $element;
    }
}

$data = array(
    'horarios' => array(),
    'grupos' => array(
        '1A' => array(
            'Juan' => array(
                'calificaciones' => array(
                    'Matematicas' => 8,
                    'Español' => 5,
                    'Ingles' => 9,
                ),
                'asistencias' => array(
                    'enero' => 20,
                    'febrero' => 10,
                    'marzo' => '',
                )
            ),
            'Damian' => array(
                'calificaciones' => array(
                    'Matematicas' => 10,
                    'Español' => '',
                    'Ingles' => 9,
                ),
                'asistencias' => array(
                    'enero' => 20,
                    'febrero' => '',
                    'marzo' => 5,
                )
            ),
        ),
        '1B' => array(
            'Mariana' => array(
                'calificaciones' => array(
                    'Matematicas' => null,
                    'Español' => 7,
                    'Ingles' => 9,
                ),
                'asistencias' => array(
                    'enero' => null,
                    'febrero' => 5,
                    'marzo' => 5,
                )
            ),
        ),
    )
);

$data = array_filter($data, 'removeEmptyElements');
var_dump($data);

¡it works!

Answer 24

I think array_walk is much more suitable here

$linksArray = array('name', '        ', '  342', '0', 0.0, null, '', false);

array_walk($linksArray, function(&$v, $k) use (&$linksArray){
    $v = trim($v);
    if ($v == '')
        unset($linksArray[$k]);
});
print_r($linksArray);

Output:

Array
(
    [0] => name
    [2] => 342
    [3] => 0
    [4] => 0
)

• We made sure that empty values are removed even if the user adds more than one space

• We also trimmed empty spaces from the valid values

• Finally, only (null), (Boolean False) and ('') will be considered empty strings

As for False it's ok to remove it, because AFAIK the user can't submit boolean values.

Answer 25

As per your method, you can just catch those elements in an another array and use that one like follows,

foreach($linksArray as $link){
   if(!empty($link)){
      $new_arr[] = $link
   }
}

print_r($new_arr);

Answer 26

try this ** **Example

$or = array(
        'PersonalInformation.first_name' => $this->request->data['User']['first_name'],
        'PersonalInformation.last_name' => $this->request->data['User']['last_name'],
        'PersonalInformation.primary_phone' => $this->request->data['User']['primary_phone'],
        'PersonalInformation.dob' => $this->request->data['User']['dob'],
        'User.email' => $this->request->data['User']['email'],
    );



 $or = array_filter($or);

    $condition = array(
        'User.role' => array('U', 'P'),
        'User.user_status' => array('active', 'lead', 'inactive'),
        'OR' => $or
    );

Answer 27

With these types of things, it's much better to be explicit about what you want and do not want.

It will help the next guy to not get caught by surprise at the behaviour of array_filter() without a callback. For example, I ended up on this question because I forgot if array_filter() removes NULL or not. I wasted time when I could have just used the solution below and had my answer.

Also, the logic is language angnostic in the sense that the code can be copied into another language without having to under stand the behaviour of a php function like array_filter when no callback is passed.

In my solution, it is clear at glance as to what is happening. Remove a conditional to keep something or add a new condition to filter additional values.

Disregard the actual use of array_filter() since I am just passing it a custom callback - you could go ahead and extract that out to its own function if you wanted. I am just using it as sugar for a foreach loop.

<?php

$xs = [0, 1, 2, 3, "0", "", false, null];

$xs = array_filter($xs, function($x) {
    if ($x === null) { return false; }
    if ($x === false) { return false; }
    if ($x === "") { return false; }
    if ($x === "0") { return false; }
    return true;
});

$xs = array_values($xs); // reindex array   

echo "<pre>";
var_export($xs);

Another benefit of this approach is that you can break apart the filtering predicates into an abstract function that filters a single value per array and build up to a composable solution.

See this example and the inline comments for the output.

<?php

/**
 * @param string $valueToFilter
 *
 * @return \Closure A function that expects a 1d array and returns an array
 *                  filtered of values matching $valueToFilter.
 */
function filterValue($valueToFilter)
{
    return function($xs) use ($valueToFilter) {
        return array_filter($xs, function($x) use ($valueToFilter) {
            return $x !== $valueToFilter;
        });
    };
}

// partially applied functions that each expect a 1d array of values
$filterNull = filterValue(null);
$filterFalse = filterValue(false);
$filterZeroString = filterValue("0");
$filterEmptyString = filterValue("");

$xs = [0, 1, 2, 3, null, false, "0", ""];

$xs = $filterNull($xs);        //=> [0, 1, 2, 3, false, "0", ""]
$xs = $filterFalse($xs);       //=> [0, 1, 2, 3, "0", ""]
$xs = $filterZeroString($xs);  //=> [0, 1, 2, 3, ""]
$xs = $filterEmptyString($xs); //=> [0, 1, 2, 3]

echo "<pre>";
var_export($xs); //=> [0, 1, 2, 3]

Now you can dynamically create a function called filterer() using pipe() that will apply these partially applied functions for you.

<?php

/**
 * Supply between 1..n functions each with an arity of 1 (that is, accepts
 * one and only one argument). Versions prior to php 5.6 do not have the
 * variadic operator `...` and as such require the use of `func_get_args()` to
 * obtain the comma-delimited list of expressions provided via the argument
 * list on function call.
 *
 * Example - Call the function `pipe()` like:
 *
 *   pipe ($addOne, $multiplyByTwo);
 *
 * @return closure
 */
function pipe()
{
    $functions = func_get_args(); // an array of callable functions [$addOne, $multiplyByTwo]
    return function ($initialAccumulator) use ($functions) { // return a function with an arity of 1
        return array_reduce( // chain the supplied `$arg` value through each function in the list of functions
            $functions, // an array of functions to reduce over the supplied `$arg` value
            function ($accumulator, $currFn) { // the reducer (a reducing function)
                return $currFn($accumulator);
            },
            $initialAccumulator
        );
    };
}

/**
 * @param string $valueToFilter
 *
 * @return \Closure A function that expects a 1d array and returns an array
 *                  filtered of values matching $valueToFilter.
 */
function filterValue($valueToFilter)
{
    return function($xs) use ($valueToFilter) {
        return array_filter($xs, function($x) use ($valueToFilter) {
            return $x !== $valueToFilter;
        });
    };
}

$filterer = pipe(
    filterValue(null),
    filterValue(false),
    filterValue("0"),
    filterValue("")
);

$xs = [0, 1, 2, 3, null, false, "0", ""];
$xs = $filterer($xs);

echo "<pre>";
var_export($xs); //=> [0, 1, 2, 3]