PHP is_null() 函数 PHP 可用的函数 is_null() 函数用于检测变量是否为 NULL。 PHP 版本要求: PHP 4 >= 4.0.4, PHP 5, PHP 7 语法 bool is_null ( mixed $var ) 参数说明: $var:要检测的变量。 返回值 如果指定变量为 NULL,则返回 TRUE,否则返回 FALSE。 实
{!! formatUser(User::find(2), false, null, null) !!} {!! formatUser(User::find(3), false, '0', null) !!} {!! formatUser(null, true, 'Some nickname', ['Category Z', 'Category A']) !!} And this is the result.At first ...
检测一个变量是否是null 可以用:is_null,但如果变量未定义用它检测会出错。因此,我们想到,检测变量是否定义可以用:isset,但是如果一个变量值是:null, 则它会返回false . 哈哈,这个问题怎么样解决呢?等待大家分享…… 检查变量存在,并且值为NULL. 复制代码代码如下: <?php function checkNull($a) { if(array_...
3.is_null(),与isset()相反。区别在于未定义的时候会报错Notice错误 if(is_null($data)){//若变量已存在、非空字符串或者非零 、array()、""、 0 、"0" 、FALSE的时候返回FALSE,若为NULL的时候返回TRUE值,未定义会报错echo"1"; }else{ echo"0"; } $data=NULL;if(is_null($data)){ echo"1";...
Check if the type of a variable is integerCheck if the type of a variable is floatCheck if a numeric value is finite or infiniteInvalid calculation will return a NaN valueCheck if a variable is numericCast float and string to integer ...
<?php # 当前目录中有一个txt文件哦 error_reporting(0); show_source(__FILE__); include("check.php"); class EeE{ public $text; public $eeee; public function __wakeup(){ if ($this->text == "aaaa"){ echo lcfirst($this->text); } } public function __get($kk){ echo "$kk,eeee...
First, the ExistValidator is now able to check relations when its new targetRelation property is set. That basically means the following rules definition is now possible:public function rules() { return [ [['customer_id'], 'exist', 'targetRelation' => 'customer'], ]; } public function ...
1.列出所有可更新的软件清单命令:yum check-update 2.更新所有软件命令:yum update 3.仅安装指定的软件命令:yum install <package_name> 4.仅更新指定的软件命令:yum update <package_name> 5.列出所有可安裝的软件清单命令:yum list 6.删除软件包命令:yum remove <package_name> 7.查找软件包 命令:yum searc...
If a save is already running, this command will fail and return FALSE. Example $redis->bgSave(); config Description: Get or Set the Redis server configuration parameters. Prototype $redis->config(string $operation, string|array|null $key = NULL, ?string $value = NULL): mixed; Return ...
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