Possible Duplicate:
Can you unset() many variables at once in PHP?
$var1 = $var2 = $tvar3 = null;
Is it okay to remove variables like this?
Are there better ways to unset couple of variables?
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are you sure you really want to unset variables in great numbers? – Your Common Sense Feb 05 '11 at 13:20
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@Col: Think of it as... variable genocide :P – BoltClock Feb 05 '11 at 13:20
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possible duplicate of http://stackoverflow.com/questions/1275766/can-you-unset-many-variables-at-once-in-php – Shakti Singh Feb 05 '11 at 13:22
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I think of it as a design flaw – Your Common Sense Feb 05 '11 at 13:22
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@Shakti Singh: You realize you have enough rep to vote to close? Anyway, good find. I just threw in my close vote. – BoltClock Feb 05 '11 at 13:22
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@BoltClock: Exceeded the daily limit to vote to close question – Shakti Singh Feb 05 '11 at 13:24
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@Shakti Singh: I see, fair enough. – BoltClock Feb 05 '11 at 13:25
1 Answers
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unset() is variadic (i.e. it takes any number of arguments and unsets them all):
unset($var1, $var2, $var3);
Also note that unset() is not the same as setting to NULL. Using unset() you actually remove the variables, whereas setting them to NULL keeps them defined, just with a "value" of NULL. Doing it either way causes isset() to return false on those variables, but they're still semantically and technically different.
Here's a quick proof:
<?php
$x = NULL;
var_dump(array_key_exists('x', $GLOBALS)); // bool(true)
unset($x);
var_dump(array_key_exists('x', $GLOBALS)); // bool(false)
?>
BoltClock
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1For the record, if anyone wants me to delete my answer just say so in a comment instead of downvoting or revoking upvotes. And even then I'll probably refuse because only this question has the `= NULL` vs `unset()` conundrum which I've taken the liberty to explain here even before the duplicate was found. Unless, of course, someone finds an older question asking about it. – BoltClock Feb 05 '11 at 13:27