PHP警告：零除

Question

function fctdeux(string $str)
{
    $nbr;

    $nbr = 0;
    while($str >= '0' && $str <= '9')
    {
        $nbr = $nbr * 10 + ($str - '0');
        $str++;
    }
    return $nbr;
}    

function testeur(string $expr)
    {
        $nbr;
        $nbr2;
        $op;

        $nbr = anal_number($expr);
        while($expr)
        {
            while($expr == ' ')
            {
                $expr++ ;
                $op = $expr;

                if($op != '/' && $op != '*' && $op != '%')
                return $nbr;
            }
            $expr++;
            $nbr2 = anal_number($expr);
            if($op = '/')
            {
            $nbr /= $nbr2;
            }else 
            if($op == '*')
            {
                $nbr *= $nbr2;
            }else
            {
                $nbr %= $nbr2;
            }
        }
        return $nbr;
    }
    echo eval_expr(2+3);

Hello I try to create a calculator for when call the function in end of code echo exemple(2+3)and in terminal call the file php exemple.php its writing result of calcul(5). I have this error :

PHP Warning: Division by zero in /home/username/project/project.php on line 125

its where I have

$nbr /= $nbr2; 

in code

Answer 1

Division by 0 is impossible. How many nothings go into X? The answer is a mathematical melt down. However, you can catch it in your code:

if ($nbr2 == 0) {
    # code to either return an error message about using 0 to divide
    # or you could return NaN (not a number) as the value.
}