如何在页面加载时使用一些PHP代码取代其他PHP代码

Question

I currently have this code in the page/div when you load it without anything in the url bar (a.k.a just index.php)

<?php echo"<h1>For all of your Citation needs!</h1>

<div >

<p>

This page is for any citations you would need to make for reports or essays. Once you enter in the needed information for your sourse, it will spit out the citations in <a href='http://owl.english.purdue.edu/owl/resource/747/01/'>MLA</a> &amp; <a href='http://owl.english.purdue.edu/owl/resource/560/01/'>APA</a> format.</p>
<p >In development is a system where your citations are stored in a database and everytime you make a new one, you will be given related reference material to help your research. Also available soon will be the ability to look up references using related fields such as:</p>

<ul>
<li>Authors</li>
<li>Ttile of Work</li>
<li>Publishing Company</li>
<li>Journal Publisher</li>
<li>Academic Source</li>
<li>Something else will go here</li>
</ul>


</div>";  ?>

When I click a link on the site to load different form data (index.php?form=book), I want that form data to take place of the stuff already in that div...for example:

<?php
switch ($_GET['form'])
{
    case 'book':
        ?>
        <form method="POST" action="thispage.php">
            <input name="" type="text" value="fghfghfghfghfghfh" />
        </form>
        <?
        break;
    case 'b': // show form b
        ?>
        <form method="POST" action="thispage.php">
            <!-- form b elements here :) -->
        </form>
        <?
        break;
    case 'c': // show form c
        ?>
        <form method="POST" action="thispage.php">
            <!-- form c elements here :) -->
        </form>
        <?
        break;
}
?>

Is there a way to have ^THIS^ block of PHP code take the place of the other block of php code when in the page/div when you click the link to load the form data?

Answer 1

Add the first block of "code" as the default for your switch statement. There are much better ways of building your page, though...

PHP manual for switch: http://php.net/manual/en/control-structures.switch.php

EDIT: Sample of your code, updated:

<?php
    switch ($_GET['form'])
    {
        case 'book':
            ?>
            <form method="POST" action="thispage.php">
                <input name="" type="text" value="fghfghfghfghfghfh" />
            </form>
            <?
            break;
        case 'b': // show form b
            ?>
            <form method="POST" action="thispage.php">
                <!-- form b elements here :) -->
            </form>
            <?
            break;
        case 'c': // show form c
            ?>
            <form method="POST" action="thispage.php">
                <!-- form c elements here :) -->
            </form>
            <?
            break;
        default:
            echo "<h1>For all of your Citation needs!</h1>

                <div >

                <p>

                This page is for any citations you would need to make for reports or essays. Once you enter in the needed information for your sourse, it will spit out the citations in <a href='http://owl.english.purdue.edu/owl/resource/747/01/'>MLA</a> &amp; <a href='http://owl.english.purdue.edu/owl/resource/560/01/'>APA</a> format.</p>
                <p >In development is a system where your citations are stored in a database and everytime you make a new one, you will be given related reference material to help your research. Also available soon will be the ability to look up references using related fields such as:</p>

                <ul>
                <li>Authors</li>
                <li>Ttile of Work</li>
                <li>Publishing Company</li>
                <li>Journal Publisher</li>
                <li>Academic Source</li>
                <li>Something else will go here</li>
                </ul>


                </div>";
                break;
    }
?>