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Juan VelasquezFlag for United States of America asked on

PHP Sytax error on Undefined Variable


I am a rank beginner in PHP.  I've just started to teach myself PHP after many years in vba and some vb.net.  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="http://www.w3.org/1999/xhtml">
    <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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Last Comment
Juan Velasquez

8/22/2022 - Mon

You have an opening if block
<?php if (!empty($error_message)) { ?>

But you never close it

<?php }?>

If you are just starting out then stick with the HTML5 doctype - no point using old doctypes
<!DOCTYPE html>
Juan Velasquez

I went ahead and checked and it looks like I am closing it on line 25

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Juan Velasquez

Oh I see.  I'm working from a sample file in the book I'm using.  I've rechecked the original sample file and that closing php tag is missing.
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It's missing from the sample or just from your code?
Juan Velasquez

It was missing from the sample
Juan Velasquez

Thanks for the help.  I am also reading the links
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