PHP code for calculator. validated but not working

Question

So I have a calculator coded in PHP and I have validated it but there is a problem with this, its not working. I have used server side validation. Validation works well. But it doesn't do any work,for example, when I give an input like 2+8, it gives an output of 8888. This is very confusing. Please help me out with this. Thanks.

HTML page is here:

 <html>
 <head>
 <title>Calculator</title>
 </head>
 <body>
 <form method = "post" action = "calc.php">
 <input type = "text" name = "val_1"/>
 <select name="operator">
 <option>+</option>
 <option>-</option>
 <option>*</option>
 <option>/</option>
 </select>
 <input type = "text" name = "val_2"/>
 <input type = "submit" value = "calculate" name = "checker"/>
 </form>
 </body>
 </html>

And here is the PHP code.

 <?php
 if(isset($_POST['checker'])) {

 #Clean all values
 function cleanStr($str){
 $str = trim($str);
 $str = addslashes($str);
 $str = htmlspecialchars($str);
 return $str;
 }
 $val_1=cleanStr($_POST['val_1']);
 $val_2=cleanStr($_POST['val_2']);
 $operator=$_POST['operator'];

 function emptyFileds($ar){
 if(!is_array($ar)){
    echo "It must be an array";
    return false;
 }
 #loop through each field to check for empty values
 foreach($ar as $key => $value){
    $value = CleanStr($value);
    if(empty($value)){
        echo $key . " must not be empty";
        return false;
    }
    }
    return true;
    }
    if(!emptyFileds($_POST)){
    exit();
    }
    if($operator==="+"){
    echo "Sum is " . $val_1+$val_2;
    }
    }
    ?>

ViRuSTriNiTy · Accepted Answer · 2016-01-01 14:48:31Z

2

Please change the original line

echo "Sum is " . $val_1+$val_2;

to

echo "Sum is " . ($val_1+$val_2);

It's a operator precedence issue as . is executed first. Therefore you append 2 to "Sum is " and then increment the string by 8 which results in this odd behavior.

Also, some nitpicking on your code, I will just name 3 issues:

requesting a parameter with cleanStr() is not a good idea, it's better to use

$val_1 = (int)trim($_POST['val_1']);

as $val_1 will be an integer after that line. This might be important for later development e.g. to compare numbers.
indent correctly, reading your code is hurting my eyes
the whole emptyFileds()thing is unnecessary, simply check whether the 3 parameters are filled or not, it's simple and it's readable.

edited Jan 1, 2016 at 14:48

answered Jan 1, 2016 at 14:27

ViRuSTriNiTy

5,2052 gold badges35 silver badges63 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Funk Forty Niner Over a year ago

Even though this answer is correct, the use of "Try" should be omitted and implies uncertainty. You need to state confidence ;-)

user5237857 Over a year ago

i changed it to $x = $val_1+$val_2. and it worked. THanks for your help anyway.

ViRuSTriNiTy Over a year ago

@Fred-ii- Yes, i was not 100 percent sure whether it would solve the issue. Now i can edit my answer and remove the "Try".

user5237857 Over a year ago

It's working fine. I want to ask you guys if it's a good code or not. I mean could it be better?

user5237857 Over a year ago

And my code is always correctly indented but stack overflow's code-paste rules annoyed me so much. Thats why i didn't indent it. I'll take care of it from now on. Thanks man.

|

Collectives™ on Stack Overflow

PHP code for calculator. validated but not working

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related