PHP将“0”视为空？

I have encounteed an issue with php treating "0" differently.

I run following script on 2 different machines:

$a = "0";
if ($a) {
    echo("helo");
}

1) Local Machine -> PHP 5.2.17 -> it treated "0" as valid and print the 'helo'

2) Server -> PHP 5.3.6 -> it treated "0" as empty/false and won't print the 'helo'

Is this due to the php configuration (if yes, what configuration) or php version?

That's how it is supposed to. PHP interprets strings in boolean context. The "0" there is equivalent to an actual 0. (See also http://www.php.net/manual/en/types.comparisons.php)

What you meant to test for is probably:

if (strlen($a)) {

if($a) should be FALSE, as per the documentation. It should also be like that on your local machine. Are you sure that on the local machine, you don't have a space after the 0 or something? ("0<space>" would be TRUE.)

Sound weird to me, I thought "0" was false, you can review here

PHP may interporate "0" as false as it would be equivilent to null/false/0.

However, it also may interporate it as a string of "0". Thus the if statement would return true, however, I think that would be a bug unless you type cast it to (string).

Like Mario said, check for the strlen($a) or check if( !empty($a) ) that way you will get your definitive answer.

I hope this helps!