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.

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 …

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.

It clarifies why the empty() function can cause errors and is not very good practice for best results code: !empty() tests both for the existence and the non-falsy value and as a reader the writers intent is not clear

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:

2011年2月14日 · Unfortunately, almost every answer here is wrong, because almost everyone didn't bother to learn the actual behavior of PHP's empty() language construct. In reality, it's impossible to replicate this command's behavior for multiple values. Because, unlike empty(), a userland function will always emit a Warning in case a tested variable doesn't ...

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

This will be empty, ie PHP will return TRUE when using if empty() on the above. So if your array has keys - either by eg a form's input names or if you assign them manually (ie create an array with database column names as the keys but no values/data from the database), then the array will NOT be empty().

2009年8月3日 · empty() does a reverse to what isset does (i.e. !isset()) and an additional check, as to whether a value is "empty" which includes an empty string, 0, NULL, false, or empty array or object False. Returns FALSE if var is set and has a non-empty and non-zero value.