[RESOLVED] eval before inserting into MySQL

[perpetualshaun]

I'm trying to do some calculations between two fields I'm pulling form the database. Here's a snippet of my MySQL query:

... field_value='".eval($_POST[$hidden['default_value']].''.$hidden['default_value_calc'])."',

And when I pull them from the database, my $hidden['default_value_calc'] == '*2' and the value I entered for the $_POST[$hidden['default_value']] == 10, so I want to get 20 here. Any ideas?

[bradgrafelman]

As the old adage goes around here, "If the answer lies in eval(), you're asking the wrong question."

How/where is $hidden['default_value_calc'] defined? Can't it simply be defined as the integer 2, so you could do:

"... field_value=" . $_POST[$hidden['default_value']] * $hidden['default_value_calc'] . ", ..."

[perpetualshaun]

Only problem is that the '' in my $hidden['default_value_calc'] filed is going to change. For this one, I want to multiply the values, but I may want to add in another. I could addd another field where I would put in the proper , +, - or /, but what happens if I need to have more equations?

Ideally, I'd really like to have just ONE field where I can write a query like this:

... field_value='" . $hidden['default_value']."'

and the default_value field (which I'm pulling from MySQL) is something like "$_POST['value2'] * 2"

Does anyone know if that's possible?

[NogDog]

I'm not 100% sure I'm following you, but an array index can be any valid PHP expression, which means you can do arithmetic inside the brackets. In a simplified version:

$arr = array(1 => 'one', 'two', 'three', 'four', 'five', 'six', 'seven');
$x = 2;
$y = 3;
echo $arr[$x * $y]; // outputs "six"

[bradgrafelman]

With variable operations, I'm not sure of a simpler way other than using eval() as you started out with, so try this:

eval('return ' . $_POST[$hidden['default_value']] .$hidden['default_value_calc'] . ';')

in place of the eval() call you had in your first post.