PHP deletes null values ​​or specified value operations in an array_PHP tutorial

We introduce the operations of arrays in PHP, such as deleting specified values ​​in the array or determining whether there is a value in the array or clearing null values. Students in need can refer to it.

First, let’s take a look at the various methods on how PHP operates null values ​​in arrays

implode(); For this function, please refer to http://www.bKjia.c0m/phper/29/2dc95be9381b4bb1753083c09fda1a36.htm
Use implode() to output the array as a string and determine whether the output string is empty. At first glance, it seems to be a good method, but unfortunately, like the previous point, it does not work for arrays with more than two dimensions. For example:

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代码如下	复制代码
$arr= array(array(),array(),array()); $str = implode(',',$arr); if(empty($str)) echo "空"; else echo "非空";

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$arr= array(array(),array(),array());

代码如下	复制代码
$arr= array("","",""); echo count($arr);

$str = implode(',',$arr);

if(empty($str)) echo "empty";

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$arr= array("d","s",""); echo in_array('', $arr);

else echo "not empty";

代码如下	复制代码
$arr= array("","",""); if(empty($arr)) echo "空"; else echo "非空";

Obviously $arr is a two-dimensional array containing three empty arrays, which should be considered empty, but the output is indeed non-empty. Judgment failed.

3. count(); Please refer to http://www.bKjia.c0m/w3school/php/func_array_count.htm

echo count($arr);

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代码如下

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function array_remove_key($array, $keys) { $num = count($keys); $num_last = $num - 1; $this_array_0 = &$array; $last_key = $keys[$num_last]; for ($i = 0; $i < $num_last; $i++) { $this_key = $keys[$i]; $this_var_name = 'this_array_' . $i; $next_var_name = 'this_array_' . ($i + 1); if (!array_key_exists($this_key, $$this_var_name)) { break; } $$next_var_name = &${$this_var_name}[$this_key]; } unset(${$next_var_name}[$last_key]); return $array; }

$arr= array("","","");

4. in_array('', $arr)); For function usage, please refer to http://www.bKjia.c0m/phper/24/c5b81a8af14b1c0928eea343f59b454a.htm

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$arr= array("d"," s",""); echo in_array('', $arr); This can only show that there are empty elements in the array, but cannot prove that the array is empty. Obviously not. 5. empty(); For function usage, please refer to http://www.bKjia.c0m/so/php+empty() This cpyeh feels similar to the previous methods

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$arr= array("","",""); if(empty($arr)) echo "empty"; else echo "not empty"; The result is still non-empty 6. Use strlen(). If there is no content, the length seems to be 1 Combined with the above example, we write a complete deletion of empty elements in the array

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function array_remove_key($array, $keys) { $num = count($keys); $num_last = $num - 1; $this_array_0 = &$array; $last_key = $keys[$num_last]; for ($i = 0; $i < $num_last; $i++) { $this_key = $keys[$i]; $this_var_name = 'this_array_' . $i; $next_var_name = 'this_array_' . ($i + 1); if (!array_key_exists($this_key, $$this_var_name)) { break; } $$next_var_name = &${$this_var_name}[$this_key]; } unset(${$next_var_name}[$last_key]); return $array; } http://www.bkjia.com/PHPjc/632230.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/632230.htmlTechArticleWe introduce the operation of arrays in php, delete the specified value in the array or determine whether there is a value in the array or clear the empty Value operation, students in need can refer to it. First let’s take a look at...