用字符串做数学[重复]

Question

Possible Duplicate:
PHP String Calculation

I am trying to make a 24-game solver.

Can i do something like this?:

$x = '*';
$a = 1;
$b = 2;

$sum = $a $x $b; //Trying something like this
$sum = $a * $b; //Actual sum

if($sum == $result) echo 'Hello World!';

Or $x as an array.

It's so confusing.

Answer 1

Are you sure you want to do that?

Why not:

$x = '*';
$a = 1;
$b = 2;

$sum1 = $x == '*' ? $a * b : false;
$sum2 = $a * $b;

if($sum1 == $sum2) echo 'Hello World!';

That'll have the same effect, without trying to eval a string.