问题
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($x) && x != "") {//for strings
doSomething();
}
回答1:
empty roughly mirrors PHP's selection of FALSE-y values:
When converting to boolean, the following values are considered FALSE:
- the boolean FALSE itself
- the integer 0 (zero)
- the float 0.0 (zero)
- the empty string, and the string "0"
- an array with zero elements
- ...
As far as why PHP works this way, or why the empty function followed suit - well, that's Just The Way It Is.
Consider using strlen($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.
来源：https://stackoverflow.com/questions/25100890/in-php-why-empty0-returns-true