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><H1
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><A
NAME="language.types.null"
>NULL</A
></H1
><P
> The special <TT
CLASS="constant"
><B
>NULL</B
></TT
> value represents
that a variable has no value. <TT
CLASS="constant"
><B
>NULL</B
></TT
> is the only possible value of type
<A
HREF="language.types.null.html"
><B
CLASS="type"
>NULL</B
></A
>.
</P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Opmerking: </B
>
The null type was introduced in PHP 4
</P
></BLOCKQUOTE
></DIV
><P
> A variable is considered to be <TT
CLASS="constant"
><B
>NULL</B
></TT
> if
<P
></P
><UL
><LI
><P
> it has been assigned the constant <TT
CLASS="constant"
><B
>NULL</B
></TT
>.
</P
></LI
><LI
><P
> it has not been set to any value yet.
</P
></LI
><LI
><P
> it has been <A
HREF="function.unset.html"
><B
CLASS="function"
>unset()</B
></A
>.
</P
></LI
></UL
>
</P
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.types.null.syntax"
>Syntax</A
></H2
><P
> There is only one value of type <TT
CLASS="constant"
><B
>NULL</B
></TT
>, and that is
the case-insensitive keyword <TT
CLASS="constant"
><B
>NULL</B
></TT
>.
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><P
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><code><font color="#000000">
<font color="#0000BB"><?php<br />$var </font><font color="#007700">= </font><font color="#0000BB">NULL</font><font color="#007700">; <br /></font><font color="#0000BB">?></font>
</font>
</code></TD
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><P
></P
></DIV
>
</P
><P
> See also <A
HREF="function.is-null.html"
><B
CLASS="function"
>is_null()</B
></A
> and <A
HREF="function.unset.html"
><B
CLASS="function"
>unset()</B
></A
>.
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