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isset

(unknown)

isset - , .

bool isset (mixed var [, mixed var [, ...]])

: isset() .

TRUE , var , FALSE .

/unset unset() , isset(). isset() FALSE , , NULL . , NULL- ("\0") PHP- NULL .

<?php $a = "test"; $b = "anothertest"; echo isset ($a); // TRUE echo isset ($a, $b); //TRUE unset ($a); echo isset ($a); // FALSE echo isset ($a, $b); //FALSE $foo = NULL; print isset ($foo); // FALSE ?>

:

<?php $a = array ('test' => 1, 'hello' => null); echo isset ($a['test']); // TRUE echo isset ($a['foo']); // FALSE echo isset ($a['hello']); // FALSE echo array_key_exists('hello', $a); // TRUE ?>

. empty() , unset() array_key_exists() .


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is_string print_r