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><A
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>uniqid</A
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><DIV
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>uniqid -- Generate a unique id.</DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN17633"
></A
><H2
>Description</H2
><DIV
CLASS="funcsynopsis"
><P
></P
><CODE
CLASS="FUNCDEF"
>int uniqid</CODE
>(string prefix, boolean
[<SPAN
CLASS="optional"
>lcg</SPAN
>]
);<P
></P
></DIV
><P
> <B
CLASS="function"
>uniqid()</B
> returns a prefixed unique identifier
based on the current time in microseconds. The prefix can be
useful for instance if you generate identifiers simultaneously on
several hosts that might happen to generate the identifier at the
same microsecond. <TT
CLASS="parameter"
><I
>prefix</I
></TT
> can be up to 114
characters long.
</P
><P
> If the optional <TT
CLASS="parameter"
><I
>lcg</I
></TT
> parameter is true,
<B
CLASS="function"
>uniqid()</B
> will add additional "combined LCG"
entropy at the end of the return value, which should make the
results more unique.
</P
><P
> With an empty <TT
CLASS="parameter"
><I
>prefix</I
></TT
>, the returned string
will be 13 characters long. If <TT
CLASS="parameter"
><I
>lcg</I
></TT
> is
true, it will be 23 characters.
</P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
The <TT
CLASS="parameter"
><I
>lcg</I
></TT
> parameter is only available in
PHP 4 and PHP 3.0.13 and later.
</P
></BLOCKQUOTE
></DIV
><P
> If you need a unique identifier or token and you intend to give
out that token to the user via the network (i.e. session cookies),
it is recommended that you use something along the lines of
<DIV
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><PRE
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> 1
2 $token = md5 (uniqid ("")); // no random portion
3 $better_token = md5 (uniqid (rand())); // better, difficult to guess
4 </PRE
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>
</P
><P
> This will create a 32 character identifier (a 128 bit hex number)
that is extremely difficult to predict.
</P
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