Adding zak's note

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@48031 c90b9560-bf6c-de11-be94-00142212c4b1
This commit is contained in:
Damien Seguy 2001-05-21 11:13:29 +00:00
parent 21b7627d0d
commit a31c6cbab0

View file

@ -810,13 +810,18 @@ show_var($proteins)
</simpara>
<para>
If a variable has been unset with <function>unset</function>,
it will no longer be <function>isset</function>.
it will no longer be <function>isset</function>. <function>isset</function>
will return <literal>FALSE</literal> if testing a variable that has been
set to <literal>NULL</literal>. Also note that a null byte (<literal>"\0"</literal>)
is not equivalent to the PHP <literal>NULL</literal> constant.
<informalexample>
<programlisting role="php">
$a = "test";
echo isset ($a); // true
echo isset ($a); // TRUE
unset ($a);
echo isset ($a); // false
echo isset ($a); // FALSE
$foo = NULL;
print isset ($foo); // FALSE
</programlisting>
</informalexample>
</para>