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Notice: Trying to get property of non-object problem(PHP)解决办法_php基础

May 17, 2016 am 09:00 AM
non-object problem

我这里实际是调用了一个zend的数据库访问的方法,使用了fetchAll方法,但由于数据库中没有该记录,所以返回的对象是null,所以我就判断对象是否为null:

复制代码 代码如下:

if($obj==null){
...
}

这么写的结果,就是产生了上面那个notice,也真是奇怪,对象为null,竟然不能访问了?

翻查资料后,发现,判断是否为null,需要这么判断:

复制代码 代码如下:

if (isset($obj)) {
echo "This var is set set so I will print.";
}

这个isset是做什么的呢?

isset函数是检测变量是否设置。

格式:bool isset ( mixed var [, mixed var [, ...]] )

返回值:

若变量不存在则返回 FALSE
若变量存在且其值为NULL,也返回 FALSE
若变量存在且值不为NULL,则返回 TURE
同时检查多个变量时,每个单项都符合上一条要求时才返回 TRUE,否则结果为 FALSE
如果已经使用 unset() 释放了一个变量之后,它将不再是 isset()。若使用 isset() 测试一个被设置成 NULL 的变量,将返回 FALSE。同时要注意的是一个 NULL 字节(”
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