issetDescriptionbool isset ( mixed var [, mixed var [, ...]] )Returns TRUE if var exists; FALSE otherwise. If a variable has been unset with unset(), it will no longer be set. isset() will return FALSE if testing a variable that has been set to NULL. Also note that a NULL byte ("\0") is not equivalent to the PHP NULL constant.
This also work for elements in arrays:
See also empty(), unset(), defined(), the type comparison tables, array_key_exists(), and the error control @ operator. | ||||||||||
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