Double operator fails

[johnrazeur]

Hello,

I am having problems when I have formula with "double" operators. E.g:

• --4+5 -> ParseError: syntax error, unexpected '4' (T_LNUMBER)
• +-4+5 -> Exception: NXP\Exception\UnknownOperatorException
• -+4+5 -> Exception: NXP\Exception\UnknownOperatorException

[phpfui]

Thanks for the issue.

I won't be able to look at this for about 2 weeks, but I thought I might be able to help you with a few observations.

First, MathExecutor will not parse anything that is not valid in PHP. So write a PHP script that does what you want and see if it is valid PHP.

Second (but related to above), I suspect that you need to do something like 10 - -4 + 5. I think the issue is the first - (or plus) sign is not associated with a value to operate on. The second +/- is associated with the following value (or should be). This could be a case of precedence which should be easy to fix if that is the case.

Hope this helps and I will take a look in July.

[fatihkizmaz]

I think that, all expressions talked in this issue (--4+5, +-4+5, -+4+5, 10--4+5) are not valid and MathExecutor lib should have no code support them. Minus or plus operators work great with both positive and negative variables and there is no problem.

    $calculator = new MathExecutor();
    $calculator->setVar("prevYearEarning",1000);
    $calculator->setVar("thisYearEarning",-500);
    echo $calculator->execute("$prevYearEarning - $thisYearEarning"); // outputs 1500

If anyone wants to execute an expression like "--4+5" successfully, the expression must be normalized before executation. For example:

    function normalizeDoubleMinusPlusOperators(string $expression):string{
        $expression = str_replace(" ", "", $expression);
        return str_replace(["--","-+","+-","++"],["+","-","-","+"], $expression);
    }
    $calculator = new MathExecutor();
    echo $calculator->execute(normalizeDoubleMinusPlusOperators("--4+5")); // outputs 9

Another option is surrounding all numbers with brackets to ensure it will execute successfully:

    $calculator = new MathExecutor();
    echo $calculator->execute("-(-4)+(5)"); // outputs 9
    echo $calculator->execute("(10)-(-4)+(5)"); // outputs 19

[phpfui]

The real test is to replicate what PHP does. Some of these expressions don't work in PHP, so no need to support them. Others are easily worked around, so not a huge priority at this point.