Master the tips for deleting null values ​​​​in arrays in PHP

Method 1: Use loops (this article takes foreach as an example)

The syntax structure is as follows:

foreach (array_expression as $value)

foreach (array_expression as $key => $value)

For specific usage, please refer to: "php foreach Detailed usage explanation》, the specific code is as follows:

<?php  
foreach( $arr as $k=>$v){  
    if( !$v )  
        unset( $arr[$k] );  
}  
?>

This method is relatively simple and easy for beginners to understand, but it is more complex and consumes more memory, so it is generally not recommended.

Method 2: Use the array_filter() function

The syntax structure is as follows:

array_filter( array $array [, callable $callback [, int $flag = 0  ]] ) : array

Pass each value in the array array to the callback function in turn . If the callback function returns true, the current value of the array array will be included in the returned result array, and the key names of the array will remain unchanged.

• # Array The array of circulating

• # 没有 没有callback function will delete all entries with the equivalent value of FALSE in array .

•            flagDetermines the parameter form received by callback: (1) ARRAY_FILTER_USE_KEY - callback accepts the key name as the only parameter.

                                                                                  (2) ARRAY_FILTER_USE_BOTH - callback accepts both key name and key value.
  

Return value: filtered array.

The specific code is as follows:

<?php   
$arr = array(   
             0 => &#39;hello&#39;,   
             1 => false,   
             2 => -1,   
             3 => null,   
             4 => &#39;&#39;  
          );   
  echo "<pre class="brush:php;toolbar:false">";
  var_dump(array_filter($arr));   
?>

The running results are as follows:

/*   array(2) {
    [0]=>
    string(5) "hello"
    [2]=>
    int(-1)
  } */

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