add math operators in function php

Question

I'm kinda new to this but I was wondering if it is possible to add some dynamic calculation into a function as a parameter.

The thing is inside my function I am formatting stuff in a consistent way but each time I want to add a certain different calculation into the parameter.

<?php
function dynamicCalculator($calculation){

 $result = $calculation;

 //some formatting
 return $result;
}

 echo dynamicCalculator('(3x5)+1');

This doesn't work of course but if anyone has an idea how this could work I would love to hear it.

http://stackoverflow.com/questions/1015242/how-to-evaluate-formula-passed-as-string-in-php — ElefantPhace, Oct 13 '13 at 21:53
[how to make a calculator in php](http://stackoverflow.com/questions/12692727/how-to-make-a-calculator-in-php) — Mark Baker, Oct 13 '13 at 22:04

score 1 · Answer 1 · answered Oct 13 '13 at 21:52

1

Your looking for RPN (Reverse Polish Notation)

Here is one example

http://pear.php.net/package/Math_RPN/

which would allow you to use

$expression = "(2^3)+sin(30)-(!4)+(3/4)";

$rpn = new Math_Rpn(); echo $rpn->calculate($expression,'deg',false);

And not have to use Eval

answered Oct 13 '13 at 21:52

exussum

18,275
8
32
65

Suggesting a library is not an answer. Please include valid code, otherwise delete and post as a comment. – Kermit Oct 13 '13 at 21:55
updated with a code example – exussum Oct 13 '13 at 21:57
Thx alot. I will have a look into this library – Obi Wan Kenobi Oct 13 '13 at 22:13

score 1 · Accepted Answer · edited Oct 13 '13 at 21:56

1

What you are looking for is the eval function.

eval('$result = (3*5)+1');

But beware to make sure you're not passing possibly harmful code to that function.

edited Oct 13 '13 at 21:56

Kermit

33,827
13
85
121

answered Oct 13 '13 at 21:53

Odie

63
5

Thx alot, I was not aware of this eval function, but it does sound 'evil':) Cheers! – Obi Wan Kenobi Oct 13 '13 at 22:13

score 0 · Answer 3 · edited May 23 '17 at 12:21

0

Use eval. eval("10+2") should return 12. Be careful though, you can also run PHP code with eval.

Someone else had a similar question on StackOverflow.

edited May 23 '17 at 12:21

Community

1
1

answered Oct 13 '13 at 21:51

sheng

1,226
8
17

score 0 · Answer 4 · answered Oct 13 '13 at 21:52

0

You could use this:

function dynamicCalculator($calculation) {
   $result = eval($calculation);
   return $result;
}

answered Oct 13 '13 at 21:52

Annabel

1,394
14
23

2

Note: in the documentation http://php.net/manual/en/function.eval.php it mentions this is dangerous as all sorts of PHP code could be smuggled into `$calculation`. – Annabel Oct 13 '13 at 21:53

add math operators in function php

4 Answers4