My PHP cashier calculator program won't work

Question

It's supposed to look like this: sample output. It will only say "Price must be a valid number" and nothing else when I test it, even when my inputs are correct numbers, it still won't calculate. I don't know what I am doing wrong here.

Here is the index.php

    <?php 
        //set default value of variables for initial page load
        if (!isset($description)) { $description = ''; } 
        if (!isset($unit_price)) { $unit_price = ''; } 
        if (!isset($quantity)) { $quantity = ''; } 
    ?> 
    <!DOCTYPE html>
    <html>
    <head>
        <title>Assignment 1</title>
        <link rel="stylesheet" type="text/css" href="YapAss1.css">
    </head>

    <body>
        <main>
        <h1>Cashier</h1>
        <?php if (!empty($error_message)) { ?>
            <p class="error"><?php echo htmlspecialchars($error_message); ?>               </p>
        <?php } ?>
        <form action="checkout.php" method="post">

            <div id="data">
                <label>Description:</label>
                <input type="text" name="investment"
                       value="<?php echo htmlspecialchars($description); ?>">
                <br>

                <label>Unit Price:</label>
                <input type="text" name="interest_rate"
                       value="<?php echo htmlspecialchars($unit_price); ?>">
                <br>

                <label>Quantity:</label>
                <input type="text" name="years"
                       value="<?php echo htmlspecialchars($quantity); ?>">
                <br>
            </div>

            <div id="buttons">
                <label>&nbsp;</label>
                <input type="submit" value="Checkout Now"><br>
            </div>

        </form>
        </main>
    </body>
    </html>

checkout.php

    <?php
        // get the data from the form
        $description = filter_input(INPUT_POST, 'description',
            FILTER_VALIDATE_FLOAT);
        $unit_price = filter_input(INPUT_POST, 'unit_price',
            FILTER_VALIDATE_FLOAT);
        $quantity = filter_input(INPUT_POST, 'quantity',
            FILTER_VALIDATE_INT);


       if ( $unit_price === FALSE )  {
            $error_message = 'Price must be a valid number.'; 
        } else if ( $unit_price <= 0 ) {
            $error_message = 'Price must be a valid number.'; 

        // validate quantity
        } else if ( $quantity === FALSE ) {
            $error_message = 'Quantity must be a valid number.';
        } else if ( $quantity <= 0 ) {
            $error_message = 'Quantity must be a valid number.';
        } else {
            $error_message = ''; 
        }


        // if an error message exists, go to the index page
        if ($error_message != '') {
            include('index.php');
            exit(); 
        }

         // calculate the future value
        $sales_tax = .07;
        $sub_total = $price * $quantity;
        $total = $subtotal * $sales_tax; 



        // apply currency and percent formatting

        $unit_price_f = '$'.number_format($unit_price, 2);
        $quantity_f = '$'.number_format($quantity, 2);
        $sub_total_f ='$'.number_format($sub_total, 2);
        $sales_tax_f = $sales_tax.'%';
        $total_f ='$'.number_format($total, 2);
    ?>
    <!DOCTYPE html>
    <html>
    <head>
        <title>Assignment 1</title>
        <link rel="stylesheet" type="text/css" href="YapAss1.css">
    </head>
    <body>
        <main>
            <h1>Checkout 12/27/2015</h1>

            <label>Item Description:</label>
            <span><?php echo $description; ?></span><br>

            <label>Price:</label>
            <span><?php echo $unit_price_f; ?></span><br>

            <label>Quantity:</label>
            <span><?php echo $quantity_f; ?></span><br>

            <label>Sub Total:</label>
            <span><?php echo $sub_total_f; ?></span><br>

            <label>Sales Tax:</label>
            <span><?php echo $sales_tax; ?></span><br>

            <label>Total:</label>
            <span><?php echo $total_f; ?></span><br>
        </main>
    </body>
    </html>

The fields you're validating bear no resemblence to the field names in your form: `years` !== `quantity`; `interest_rate` !== `unit_price`; `investment` !== `description` — Mark Baker, Jan 12 '16 at 23:39
holy crap. I reviewed it so many times and still overlooked that. Thank you very much — agentmg123, Jan 13 '16 at 18:03

score 0 · Answer 1 · answered Jan 12 '16 at 23:44

On the page checkout.php you have the if statement:

if ( $unit_price === FALSE )

So you are checking for a boolean while this value must be an integer. I'm just wildguessing that your objective was to check if this variable was set. Adjust this by changing the if statement to:

if (!isset(($unit_price))

The same is going on for the variable $quantity. By making this adjustment u can remove the php you have on the top 6 lines of index.php. Goodluck!

score 0 · Accepted Answer · answered Jan 12 '16 at 23:46

Here is the fault:

 $description = filter_input(INPUT_POST, 'description',
            FILTER_VALIDATE_FLOAT);
        $unit_price = filter_input(INPUT_POST, 'unit_price',
            FILTER_VALIDATE_FLOAT);
        $quantity = filter_input(INPUT_POST, 'quantity',
            FILTER_VALIDATE_INT);

You have incorrect input names submitted here.

New Code

 $description = filter_input(INPUT_POST, $_POST['investment'],
            FILTER_VALIDATE_FLOAT);
        $unit_price = filter_input(INPUT_POST, 'interest_rate',
            FILTER_VALIDATE_FLOAT);
        $quantity = filter_input(INPUT_POST, 'years',
            FILTER_VALIDATE_INT);

You also have some undefined variables in your code. You need to recheck all the variables you are using.

My PHP cashier calculator program won't work

2 Answers2