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Who can tell me the difference between is_null(), =="&q
Posted: Wed Jun 04, 2003 9:25 am
by detrox
A form has a text area named comment.
Now, I wanna know whether comment is empty.If I use
Code: Select all
if is_null($_GETї"comment"]);
It does not work.
Only
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if ($_GETї"comment"] == "");
can work.
Who can tell me why?
Thanks very much.
Posted: Wed Jun 04, 2003 9:28 am
by twigletmac
If you are testing for a NULL value you can use
is_null(), however, if you are testing to see if a variable is empty (as you are) then you should use
empty().
Mac
Posted: Wed Jun 04, 2003 11:48 pm
by detrox
So it means that a null variable is a variable whose value is null.A empty variable doesn't contain anything?
That is so different from C/C++
Posted: Thu Jun 05, 2003 12:45 am
by Sevengraff
Posted: Thu Jun 05, 2003 2:49 am
by volka
empty() is the opposite of ==TRUE
therefor an empty string like '' is empty as is the number 0 and the values FALSE & NULL.
is_null() only checks for NULL.
Posted: Thu Jun 05, 2003 6:19 am
by detrox
Excuse me, volka.I do not understand about 'empty() is the opposite of ==TRUE'. Is that mean 'If (empty($a))' is the same as 'If $a == FALSE'? That's puzzled.
Posted: Thu Jun 05, 2003 6:22 am
by volka
almost yes
+ empty() does not throw a warning if $a is undefined.
see also:
http://php.net/empty
http://www.php.net/manual/en/language.t ... an.casting
Posted: Thu Jun 05, 2003 6:27 am
by detrox
I got it, Thanks very much.