如何避免未定义的偏移 [英] How to avoid undefined offset

问题描述

如何轻松避免出现此错误/通知:

How can you easily avoid getting this error/notice:

Notice: Undefined offset: 1 in /var/www/page.php on line 149

...在此代码中:

list($func, $field) = explode('|', $value);

explode不一定总是返回两个值，但是如果您想使用list()，那么如何轻松地避免该通知呢?

There are not always two values returned by explode, but if you want to use list() how can you then easily avoid the notice?

推荐答案

list($func, $field) = array_pad(explode('|', $value, 2), 2, null);

两项更改:

• 它将explode()返回的数组的大小限制为2.看来，只需要这个就可以了.
• 如果返回的值少于两个，它将附加null直到数组包含2个值.有关更多信息，请参见手册:array_pad()

• It limits the size of the array returned by explode() to 2. It seems, that no more than this is wanted
• If there are fewer than two values returned, it appends null until the array contains 2 values. See Manual: array_pad() for further information

这意味着，如果$value中没有|，则$field === null.当然，您可以使用要定义为$field(而不是null)默认值的每个值.也可以交换$func和$field

This means, if there is no | in $value, $field === null. Of course you can use every value you like to define as default for $field (instead of null). Its also possible to swap the behavior of $func and $field

list($func, $field) = array_pad(explode('|', $value, 2), -2, null);

当$value中没有|时，现在$func是null.

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