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php-manual-en-4.3.0-2mdk.noarch.rpm

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>eval</H1
><DIV
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><A
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></A
><P
>    (PHP 3, PHP 4 )</P
>eval&nbsp;--&nbsp;Evaluate a string as PHP code</DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN55456"
></A
><H2
>Description</H2
>mixed <B
CLASS="methodname"
>eval</B
> ( string code_str)<BR
></BR
><P
>&#13;     <B
CLASS="function"
>eval()</B
> evaluates the string given in
     <TT
CLASS="parameter"
><I
>code_str</I
></TT
> as PHP code. Among other things,
     this can be useful for storing code in a database text field for
     later execution.
    </P
><P
>&#13;     There are some factors to keep in mind when using
     <B
CLASS="function"
>eval()</B
>. Remember that the string passed must
     be valid PHP code, including things like terminating statements
     with a semicolon so the parser doesn't die on the line after the
     <B
CLASS="function"
>eval()</B
>, and properly escaping things in
     <TT
CLASS="parameter"
><I
>code_str</I
></TT
>.
    </P
><P
>&#13;     Also remember that variables given values under
     <B
CLASS="function"
>eval()</B
> will retain these values in the main
     script afterwards.
    </P
><P
>&#13;     A <TT
CLASS="literal"
>return</TT
> statement will terminate the evaluation of 
     the string immediately. In PHP 4, <B
CLASS="function"
>eval()</B
> returns
     <TT
CLASS="constant"
><B
>NULL</B
></TT
> unless <A
HREF="function.return.html"
><B
CLASS="function"
>return()</B
></A
> is called in the evaluated
     code, in which case the value passed to <A
HREF="function.return.html"
><B
CLASS="function"
>return()</B
></A
> is
     returned. In PHP 3, <B
CLASS="function"
>eval()</B
> does not return a value.
    </P
><P
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><DIV
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><A
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></A
><P
><B
>Example 1. 
       <B
CLASS="function"
>eval()</B
> example - simple text merge
      </B
></P
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><TR
><TD
><PRE
CLASS="php"
>&#60;?php
$string = 'cup';
$name = 'coffee';
$str = 'This is a $string with my $name in it.&#60;br&#62;';
echo $str;
eval ("\$str = \"$str\";");
echo $str;
?&#62;</PRE
></TD
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></TABLE
><P
>&#13;       The above example will show:
       <TABLE
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><TR
><TD
><PRE
CLASS="screen"
>This is a $string with my $name in it.
This is a cup with my coffee in it.</PRE
></TD
></TR
></TABLE
>
      </P
></DIV
></TD
></TR
></TABLE
>
    </P
><DIV
CLASS="tip"
><BLOCKQUOTE
CLASS="tip"
><P
><B
>Tip: </B
>As with anything that outputs
its result directly to the browser, you can use the <A
HREF="ref.outcontrol.html"
>output-control functions</A
> to capture
the output of this function, and save it in a
<A
HREF="language.types.string.html"
><B
CLASS="type"
>string</B
></A
> (for example).</P
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