eval or not to eval?

Anon

Does anybody know how I can do the following in PHP.
I have a STRING that gets created dynamically. (e.g. $string="2+3+4" or $string="1+5+12" etc....)

I want to do the following:

$result=$string/3

and get a numerical result in $result.

So for example if $string="1+2+3" then $result would be 2. That is 6/2.
Eval was the first thing that came to mind. But it does not seem to work like with other languages.

Also if I have a string like $string="1,2,3"
and I want to use max($string) to get 3 as a result, eval does not seem to work.

Any thoughts? Please let me know.

Anon

I tried the following and it worked:

<?php
$string = '1+2+3';
$code = "\$result = (($string) / 3);";
eval($code);
?>

I think with eval you have to have the whole statement as the parameter, including the semicolon - you can't just say $total=eval('1+2+3'), like you can in Perl.

-Keegan

Anon

Correct.
The manual says it all really.
I wonder why people refuse to read it.

-- quote from manual --
eval

                    (unknown)

                    eval -- Evaluate a string as PHP code

                    Description

                    mixed eval (string code_str)

                    eval() evaluates the string given in code_str as PHP code. Among other things, this can be useful for storing code in a database text field for later execution. 

                    There are some factors to keep in mind when using eval(). 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 eval(), and properly escaping things in code_str. 

                    Also remember that variables given values under eval() will retain these values in the main script afterwards. 

                    A return statement will terminate the evaluation of the string immediatley. In PHP 4 you may use return to return a value that will become the result of the eval()
                    function while in PHP 3 eval() was of type void and did never return anything.

Example 1. Eval() example - simple text merge

                        <?php
                        $string = 'cup';
                        $name = 'coffee';
                        $str = 'This is a $string with my $name in it.<br>';
                        echo $str;
                        eval ("\$str = \"$str\";");
                        echo $str;
                        ?>

-- end quote --

Anon

Thank you very much Keegan. It works for me too. I apreciate your help.