unset

Description

unset() destroys the specified variables and returns true.

Example 1. Unset() example // destroy a single variable unset ($foo); // destroy a single element of an array unset ($bar['quux']); // destroy more than one variable unset ($foo1, $foo2, $foo3);

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.

function destroy_foo() {
    global $foo;
    unset($foo);
}

$foo = 'bar';
destroy_foo();
echo $foo;
      

bar
      

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";
      

something
something
      

If a static variable i