如何在 PHP 中删除数组中的空值

### Answer: Use the PHP array_filter() function
You can simply use the PHP `array_filter()` function to remove or filter empty values from an array. This function typically filters the values of an array using a callback function.

However, if no callback function is specified, all empty entries of array will be removed, such as "" (an empty string), `0` (0 as an integer), `0.0 `(0 as a float), `"0"` (0 as a string), `NULL`, `FALSE` and `array()` (an empty array). Let's try out an example to understand how it actually works:

```php
<?php
$array = array("apple", "", 0, 2, null, -5, "0", "orange", 10, false);
var_dump($array);
echo "<br>";

// Filtering the array
$result = array_filter($array);
var_dump($result);
?>
```
In the above example the values `0` and `"0"` are also removed from the array. If you want to keep them, you can define a callback function as shown in the following example:

```php
<?php
$array = array("apple", "", 0, 2, null, -5, "0", "orange", 10, false);
var_dump($array);
echo "<br>";
 
// Defining a callback function
function myFilter($var){
    return ($var !== NULL && $var !== FALSE && $var !== "");
}

// Filtering the array
$result = array_filter($array, "myFilter");
var_dump($result);
?>
```
The callback function `myFilter()` is called for each element of the array. If `myFilter()` returns `TRUE`, then that element will be appended to the result array, otherwise not.