2012年1月8日 · Its worth noting - and I only found this out after nearly 9 years of PHP coding that the best way of checking any variable exists is using the empty() function. This is because it doesn't generate errors and even though you turn them off - PHP still generates them! empty() however won't return errors if the variable doesn't exist.

As mentioned in the comments the lack of warning is also important with empty() PHP Manual says. empty() is the opposite of (boolean) var, except that no warning is generated when the variable is not set. Regarding isset. PHP Manual says. isset() will return FALSE if testing a variable that has been set to NULL

Según la documentación de isset():. Devuelve true si la variable existe y tiene un valor distinto de null, false de lo contrario.

2014年11月25日 · true if the variable is set and does not equal empty string, 0, '0', NULL, FALSE, blank array. it is clearly not the same as isset. if the variable does not equal an empty string, if the variable isnt set its an empty string. if the variable coerces to true, if …

2012年3月7日 · @deceze It has been a while but you're right: empty does seem to absorb/suppress all notices/errors, avoiding the "Undefined offset/index" notice to be thrown due to a non-existing key in the array (even in PHP v4.4.9, just tested :). I adjusted the answer, thanks for pointing that out!

In the PHP world, apparantly uninitialized variables have the Null value, and isset on such a variable returns FALSE. For arrays and strings, PHP follows the convention that "empty" means "has no members" although arrays and strings are not technically sets. PHP apparantly has this funny idea that 0 and 0.0 are also "empty", by PHP design.

To be clear, the empty square brackets syntax for appending to an array is simply a way of telling PHP to assign the indexes to each value automatically, rather than YOU assigning the indexes. Under the covers, PHP is actually doing this:

2009年8月16日 · <form action="test.php" method="post"> ^^^^^ Okay, this was stupid and I will be embarassing myself in public, but I knocked up a little test script for something in PHP and when my $_POST array was empty, StackOverflow is the first place I looked and I didn't find the answer I needed. I had only written

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2019年11月6日 · From PHP Manual – empty(): empty — Determine whether a variable is empty In other words, it will return true if the variable is an empty string, false, array(), NULL, “0?, 0, and an unset variable.