注: unset() is a language construct.
unset() destroys the specified
variables. Note that in PHP 3,
unset() will always return
TRUE (actually, the integer value 1). In PHP 4,
however, unset() is no longer a true
function: it is now a statement. As such no value is
returned, and attempting to take the value of unset() results in a parse error.
The behavior of unset() inside
of a function can vary depending on what type of variable you
are attempting to destroy.
If a globalized variable is
unset() inside of a function, only the local variable is
destroyed. The variable in the calling environment will
retain the same value as before
unset() was called.
If a variable that is PASSED BY REFERENCE is unset() inside of a function, only the local
variable is destroyed. The variable in the calling
environment will retain the same value as before unset() was called.
function foo( $bar) { unset($bar); $bar = "blah"; } $bar = 'something'; echo "$bar\n"; foo($bar); echo "$bar\n"; |
If a static variable is unset()
inside of a function, unset()
destroyes the variable and all its references.
If you would like to unset() a
global variable inside of a function, you can use the $GLOBALS array to do so: