troubleshooting Question

PHP Sytax error on Undefined Variable

Avatar of Juan Velasquez
Juan VelasquezFlag for United States of America asked on
8 Comments2 Solutions399 ViewsLast Modified:

I am a rank beginner in PHP.  I've just started to teach myself PHP after many years in vba and some  I am getting an undefined variable error when I first run the program.  From what I've read this is because the variables are not set when the application is started.  I'm trying to use the ISSET function to check the value of  variable.  If they are set, I would then like to execute the code. It looks like I'm still getting an error on the </html> tag.  It's some sort of syntax error but I'm not finding it.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns="">
    <title>Future Value Calculator</title>
    <link rel="stylesheet" type="text/css" href="main.css"/>

    <div id="content">
    <h1>Future Value Calculator</h1>
    <?php if (!empty($error_message)) { ?>
        <p class="error"><?php echo $error_message; ?></p>
    <form action="display_results.php" method="post">

        <div id="data">
            <label>Investment Amount:</label>
            <input type="text" name="investment"

//this is where I put the isset function ----------------------------

            <?php if(isset($investment)) { ?>
                   value="<?php echo $investment; ?>"/><br />
            <?php } ?>

            <label>Yearly Interest Rate:</label>
            <input type="text" name="interest_rate"
                   value="<?php echo $interest_rate; ?>"/><br />

            <label>Number of Years:</label>
            <input type="text" name="years"
                   value="<?php echo $years; ?>"/><br />

        <div id="buttons">
            <input type="submit" value="Calculate"/><br />

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