How could I display the source file.php in HTML?

Question

I have the following PHP script (file.php) which shows the current time and displays the user's input:

Current time:

<?php

$time=time();
$actual_time=date('H:i:s',$time);
echo $actual_time;

//show user input
$enter=@$_POST['enter'];
echo '<br>Input: '.$enter;

?>

<form action="" method="POST">
    <input type="text" name="enter">
    <input type="submit" value="Refresh">
</form>

By default the page shows this:

If I enter e.g. <strong>test</strong>, I see this:

And if I enter <iframe src="file.php"></iframe>, I can reload the page in a smaller window:

So, now, how could I display the raw PHP script (file.php) by submitting some certain HTML code in the INPUT text field?

Answer 1

<?php

// Disable a WebKit security feature
// which would prevent from showing the source code.
header('X-XSS-Protection: 0');

if (isset($_GET['source']) || isset($_POST['source'])) {
        $source = file_get_contents(__FILE__);

        // To prevent this control from showing up
        // in the output source code
        // enable the code below.
        /*
        $lines_to_remove = 26;
        $source = explode("\n", $source, $lines_to_remove);
        $source = $source[$lines_to_remove - 1];
        */

        $source = highlight_string($source, true);
        echo $source;

        return;
}

?>
Current time:

<?php


$time=time();
$actual_time=date('H:i:s',$time);
echo $actual_time;

//show user input
$enter=@$_POST['enter'];
echo '<br>Input: '.$enter;

?>

<form action="" method="POST">
    <input type="text" name="enter">
    <input type="submit" value="Refresh">
</form>

Answer 2

First

htmlspecialchars — Convert special characters to HTML entities

$new = htmlspecialchars("<a href='test'>Test</a>", ENT_QUOTES);
echo $new;

//This would be the output
&lt;a href=&#039;test&#039;&gt;Test&lt;/a&gt;

//browser will display
<a href='test'>Test</a>

Second

htmlentities -Convert all applicable characters to HTML entities

$str = "A 'quote' is <b>bold</b>";

echo htmlentities($str);

// Outputs: A 'quote' is &lt;b&gt;bold&lt;/b&gt;

echo htmlentities($str, ENT_QUOTES);
// Outputs: A &#039;quote&#039; is &lt;b&gt;bold&lt;/b&gt;

In browser it woulbe displayed:

A 'quote' is <b>bold</b>