PHP: empty() functionLast update on August 19 2022 21:50:39 (UTC/GMT +8 hours) DescriptionThe empty() function is used to check whether a variable is empty or not. Often, you may encounter a scenario, when you need to code in fashion if a variable is empty or another thing if it...
Example of empty() function Here, declare two variable one with empty string value and another with some text value and check variable whether is empty or not using php empty() function. <?php$str1=0;$str2='Meera';if(empty($str1)){echo"The str1 is empty or 0 ";}else{echo"The ...
PHP开发时,当你使用empty检查一个函数返回的结果时会报错:Fatal error: Can't use function return value in write context 例如: <?php echoempty(strlen('be-evil.org')); 到PHP手册里面查看,在empty函数描述的地方有以下文字: Note:empty()only checks variables as anything else will result in a parse ...
实际上,empty不是一个函数,而是一个语言结构。语言结构是在PHP程序运行前编译好的,因此不能像之前那样简单地搜索PHP_FUNCTION empty或ZEND_FUNCTION empty查看其源码。要想看empty等语言结构的源码,先要理解PHP代码执行的机制。 PHP执行代码会经过4个步骤,其流程图如下所示: 在第一个阶段,即Scanning阶段,程序会扫描...
通常的函数是通过ZEND_FUNCTION(xxx) 这种宏定义来实现的,这个规范很好理解,也很容易读懂源码。 但empty(), isset()的处理比较特殊,类似的还有echo, eval等。 准备工作 用于查看PHP opcode的扩展vld,下载: http://pecl.php.net/package/vld PHP源码,分支 => remotes/origin/PHP-5.6.14 ...
Can't use function return value in write context E:\www\www.itokit.com\js\Lib\Action\Jsadmin\CommonAction.class.php 第 16 行. 这个错误的原因是由于:empty函数参数必须为variable,不能为其它函数的返回值,包括str_replace,trim等等 而我的empty里使用了cookie有返回值的函数。所以就报了这个错误的了。
以下是php_is_type函数的具体实现:static inline void php_is_type(INTERNAL_FUNCTION_PARAMETERS, int type) { zval *arg; ZEND_PARSE_PARAMETERS_START(1, 1) Z_PARAM_ZVAL_DEREF(arg) ZEND_PARSE_PARAMETERS_END_EX(RETURN_FALSE); if (Z_TYPE_P(arg) == type) { if (type == IS_OBJECT) { ...
php empty()函数的用法 说明 1、用于检测变量是否为空。 2、如果变量不存在,或者其值等于FALSE,则被认为不存在。如果没有变量,empty()就不会发出警告。...语法 bool empty ( mixed $var ) 实例 //empty()函数检查一个变量是否为空 public function check_empty(){ ...$a =''; var_dump(empty($a))...
“0” is false weather its string or int when use empty() and isset() function in php correct your self Reply Virendra Chandak July 19, 2018 at 7:57 AM PDT Hey Gayan, When used empty() on “0” as a string it is false, but when used on int it is true. Can you provide the...
A small enhancement: The where() method already provides a lot of conditions. However, I just came across the need to check in a query if a field is null or an empty string. Like empty() in PHP. Could this be done by Yii? AFAIK one needs...