in php, why empty(“0”) returns true?

Question

According to php documentation, the following expressions return true when calling empty($var)

• \"\" (an empty string)
• 0 (0 as an integer)

Answer 1

empty roughly mirrors PHP's selection of FALSE-y values:

When converting to boolean, the following values are considered FALSE:

• the boolean FALSE itself
• the integer 0 (zero)
• the float 0.0 (zero)
• the empty string, and the string "0"
• an array with zero elements
• ...

As far as why PHP works this way, or why the empty function followed suit - well, that's Just The Way It Is.

Consider using strlen($x) (this is especially well-suited to sources like $_POST which are all string values) to determine if there is a non-empty string, including "0".

The final form I use would then be: isset($x) && strlen($x), with any additional processing applied knowing there was some post data.