performing math on number array values in PHP

Question

Ok, not exactly what I was expecting...I didn't know my code was so ureadable...sorry! What can I do to fix it? I really would like to just accomplish the (what I thought was) simple math to get totals. I've looked everywhere and read so much information on arrays and obviously I am just not grasping the concept...any more help is welcomed and would be GREATLY appreciated!

I’m creating a mock order form that has radio buttons, checkboxes and uses arrays to show the total purchase amount. I have a form that is working except for that I can't get the total amount from the two different arrays i have. $total = $extras + $additional isn't working and honestly, i should have known it couldn’t be that easy! ... Any suggestions on what formula to use so that I can get a total dollar amount of all of the options that are selected? Also, can anyone help me so that checkbox items are listed in a new row, and not a whole new table?

Thanks in advance!

A couple more things: I have to keep this in a redux and would like to keep the output in the table like it is...other than that, feel free to change whatever you want/need.

I’m new to PHP arrays and seem to only be having difficulties when it comes to their values, but since I know how important arrays are in PHP I would like to see how they work!

    <?php

    /*This stuff is only here because I want to make sure
    there are 2 decimal places in the final numbers since
    I'm dealing in "money" values*/
    $total = number_format ($total,2);
    $value = number_format ($value,2);
    $additional = number_format ($additional,2);


    $value = array("Short Trip"=>15.99, "Long Trip"=>28.99, "Overnight"=>10.99 "Forever"=>99.99);

    if(isset($_POST['travel'])) {

    $extras = array("Hair Brush"=>1.50, "Shampoo"=>1.50, "Toothpaste"=>1.50, 
    "Cream Rinse"=>1.50, "Tooth Brush"=>1.50, 
    "Shower Cap"=>1.50, "Washcloth"=>1.50, "Mouthwash"=>1.50);

    if (isset($_POST['extras'])) {
    foreach ($_POST['extras'] as $additional) {
    echo "<table border =\"2\">
    <tr><td>Item</td><td>Charges</td></tr>
    <tr><td>".$_POST['travel']."</td>
    <td> $".$value[$_POST['travel']]."</td></tr>
    <tr>

    <td>".$additional."</td>
    <td> $".$extras[$additional]."</td>

    </tr>
    <tr><td>Your total</td> <td>".$total."</td></tr>
    </table>";

    }
    }
    }

    ?>


    <html>
    <body>
    <form action="" method="post">

    <table border="2">
    <tr>
    <td colspan="2" align="center" scope="col">Stay Information</td>
    </tr>
    <tr>
    <td><input type="radio" name="travel" value="Short Trip" />Short trip $15.99</td>
    <td><input type="radio" name="travel" value="Long Trip" />Long trip $28.99</td>
    </tr>
    <tr>
    <td><input type="radio" name="travel" value="Overnight" />Overnight $10.99</td>
    <td><input type="radio" name="travel" value="Forever" />Forever $99.99</td>
    </tr>
    </table>
    <table border="2">
    <tr>
    <td colspan="2" scope="col">What will you need?($1.50 each)</td>
    </tr>
    <tr>
    <td><input type="checkbox" name="extras[]" value="Hair Brush" />Hair Brush</td>
    <td><input type="checkbox" name="extras[]" value="Shampoo" />Shampoo</td></tr>
    <tr>
    <tr><td><input type="checkbox" name="extras[]" value="Toothpaste" />Toothpaste</td>
    <td><input type="checkbox" name="extras[]" value="Cream Rinse" />Cream Rinse</td></tr>
    </tr>
    <tr>
    <td><input type="checkbox" name="extras[]" value="Tooth Brush" />Tooth Brush</td>
    <td><input type="checkbox" name="extras[]" value="Shower Cap" />Shower Cap</td></tr>
    <tr>
    <tr><td><input type="checkbox" name="extras[]" value="Washcloth" />Washcloth</td>
    <td><input type="checkbox" name="extras[]" value="Mouthwash" />Mouthwash</td></tr>
    </tr>

    <tr><td colspan="2">
    <input type="submit" value="Submit"></td></tr>
    </table>
    </form>
    </body>
    </html>

you are echoing the table before the html tag. not a good way of doing it — Ibu
– Ibu, Commented Jun 24, 2011 at 6:02
You do not want to store monetary values as floats (literal 15.99 in your source). The exact value changes as soon as that value is parsed by PHP. It'll work most of the time, but you may stumble into unexpected rounding results someday. Google for "float precision". — deceze
– deceze ♦, Commented Jun 24, 2011 at 6:13

Doug Owings · Accepted Answer · 2011-06-24 16:25:14Z

2

The comments have pointed out some issues, the main one being the formatting of your code. Indeed, when trying to figure out what one did wrong in a script, confusing formatting can add hours of wasted time.

The first thing you might notice is that your $value array is missing a comma.

$value = array("Short Trip"=>15.99, "Long Trip"=>28.99, "Overnight"=>10.99 "Forever"=>99.99)
//  comma here -----------------------------------------------------------^

Formatting is to some degree a matter of style, but the main point is readability, so that you can more easily catch mistakes like this.

Here is a condensed version of something what your script might look like:

<?php

$value = array(
    "Short Trip" => 15.99, 
    "Long Trip" => 28.99, 
    "Overnight" => 10.99,
    "Forever" => 99.99
);

$extras = array(
    "Hair Brush" => 1.50, 
    "Shampoo" => 1.50, 
    "Toothpaste" => 1.50, 
    "Cream Rinse" => 1.50, 
    "Tooth Brush" => 1.50, 
    "Shower Cap" => 1.50, 
    "Washcloth" => 1.50, 
    "Mouthwash" => 1.50
);

// combine condititions
if (isset($_POST['travel']) && isset($_POST['extras'])) {

    $total = $value[$_POST['travel']];
    // start table html (before foreach loop)

    // store html in a variable to print later
    $html = "<table border =\"2\">
              <tr>
               <td>Item</td>
               <td>Charges</td>
              </tr>
              <tr>
                <td>" . $_POST['travel'] . "</td>
                <td> $" . $total . "</td>
              </tr>";

    foreach ($_POST['extras'] as $additional) {
        // add a row per extra
        $html .= "<tr>
                    <td>" . $additional . "</td>
                    <td> $" . $extras[$additional] . "</td>
                  </tr>";

        // increment total
        $total += $extras[$additional];
    }
    $html .= "<tr>
               <td>Your total</td> 
               <td>" . $total . "</td>
              </tr>
            </table>";

}
?>
<html>
<body>
<form action="" method="post">

<?php 
if (isset($html)) {
    echo $html;
}
?>

<table border="2">
.....

There may be further issues, as I'm not clear on which part you're having trouble, but they will now be much easier to debug.

edited Jun 24, 2011 at 16:25

answered Jun 24, 2011 at 6:55

Doug Owings

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1 Comment

Craig Over a year ago

Wow! Thanks so much for your help! I do understand the powers of formatting, and to be fair, some of mine was lost copy/pasting in here. Your post is awesome, but I have to admit I have one more question. Nothing is making me feel more stupid than looking over your code and trying it out and getting errors (on line 22 about the { .) I know enough PHP to know it should be there so is this just a problem w/ me again? I promise I'm not normally this slow. I'm usually a pretty good programmer, but I'm new to PHP and so far I feel as though I just want to have a nervous breakdown over it! LOL

Henry · Accepted Answer · 2011-06-24 15:49:03Z

0

Impressive code Doug. I hate to tell you, but I think there may be one more error. I can't figure out why, but if anyone else runs this code they would see that the math is only performed on his $1.50 "additional" items-- There isn't a working collective total.

answered Jun 24, 2011 at 15:49

Henry

1

1 Comment

Doug Owings Over a year ago

Thanks for pointing this out. Fwiw, I was more interested in getting the OP started than producing a working script. The error is fixed (maybe): $total = $value[$_POST['total']]. (You should probably post comments like this as comments and not independent answers.) Cheers.

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