They do not throw an Exception when accessing an undefined array key, so we can safely check for key or value presence in the array.Checking For Model PresenceWorking with Eloquent is relatively straightforward.
PHP中,”NULL” 和 “空” 是2个概念。 isset 主要用来判断变量是否被初始化过 empty 可以将值为 “假”、”空”、”0″、”NULL”、”未初始化” 的变量都判断为TRUE is_null 仅把值为 “NULL” 的变量判断为TRUE var == null 把值为 “假”、”空”、”0″、”NULL” 的变量都判断为TRUE var ...
在PHP 中,可以使用 is_null() 函数来判断一个变量是否为空。这个函数接受一个参数,如果参数为空,则返回 true,否则返回 false。下面是一个简单的示例: <?php $variable = null; if (is_null($variable)) { echo "The variable is null."; } else { echo "The variable is not null."; } ?> 复制...
$value . ''; if (!isset($value)) { echo 'isset()==false'; } if (empty($value)) { echo 'empty()==true'; } if (!$value) { echo 'self==false'; } if (is_null($value)) { echo 'is_null()==true'; } } 输出结果: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ...
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 $value = NULL): mixed; Return ...
PHP 中判断变量类型及是否为空主要涉及到的函数有gettype(),isEmpty(),isset(),is_null(),下表详细说
;;指示被指定使用如下语法:;指示标识符=值;directive=value;指示标识符 是*大小写敏感的*-foo=bar 不同于FOO=bar。;;值可以是一个字符串,一个数字,一个PHP常量(如:E_ALLorM_PI),INI常量中的;一个(On,Off,True,False,Yes,No and None),或是一个表达式;(如:E_ALL&~E_NOTICE),或是用引号括起来的...
1$request->validate([ 2 'credit_card_number' => 'required_if:payment_type,cc' 3]);If this validation rule fails, it will produce the following error message:1The credit card number field is required when payment type is cc.Instead of displaying cc as the payment type value, you may ...
The attempt method accepts an array of key / value pairs as its first argument. The values in the array will be used to find the user in your database table. So, in the example above, the user will be retrieved by the value of the email column. If the user is found, the hashed ...
if(isset($data)){//isset() 若变量已存在、非空字符串或者非零 、array()、""、 0 、"0" 、FALSE的时候返回TRUE,若为NULL、未定义的时候返回FALSE值echo"1"; }else{ echo"0"; } $data=NULL;if(isset($data)){ echo"1"; }else{ echo"0"; }...