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)
• 0.0 (0 as a float)
• "0" (0 as a string)
• NULL
• FALSE
• array() (an empty array)
• $var; (a variable declared, but without a value)

i've found how to "solve" the problem by using empty($var) && $var != 0 but why php developers did it? i think it is ridiculous, suppouse you have this code:

if (empty($_POST["X"])) {
    doSomething();
}

i think "0" is not empty, empty is when there is nothing!!! maybe it's better to use

if (isset($x) && x != "") {//for strings
    doSomething();
}

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.