When the documentation says that the PHP parser ignores everything outside the <?php ... ?> tags, it means literally EVERYTHING. Including things you normally wouldn't consider "valid", such as the following:
<html><body>
<p<?php if ($highlight): ?> class="highlight"<?php endif;?>>This is a paragraph.</p>
</body></html>
Notice how the PHP code is embedded in the middle of an HTML opening tag. The PHP parser doesn't care that it's in the middle of an opening tag, and doesn't require that it be closed. It also doesn't care that after the closing ?> tag is the end of the HTML opening tag. So, if $highlight is true, then the output will be:
<html><body>
<p class="highlight">This is a paragraph.</p>
</body></html>
Otherwise, it will be:
<html><body>
<p>This is a paragraph.</p>
</body></html>
Using this method, you can have HTML tags with optional attributes, depending on some PHP condition. Extremely flexible and useful!
Uscita dal modo HTML
Tutto ciò che esiste fuori dai tag di apertura e chiusura è ignorato dall'analizzatore PHP, il che permette di avere contenuto misto nei file PHP. Questo permette a PHP di essere incluso nei documenti HTML, per esempio per creare modelli.
<p>Questo sarà ignorato dea PHP e verrà visualizzato nel browser.</p>
<?php echo 'Questo invece sarà interpretato.'; ?>
<p>Pure questo sarà ignorato dea PHP e verrà visualizzato nel browser.</p>Utilizzo di strutture con condizioni
Example #1 Escape avanzato con le condizioni
<?php if ($expression == true): ?>
Questo sarà viualizzato se l'espressione $expression è vera.
<?php else: ?>
Altrimenti verrà visualizzata questa linea.
<?php endif; ?>Nella visualizzazione di grossi blocchi di testo uscire dalla modalità di parsing del codice PHP è generalmente più efficiente che inviare il tutto tramite echo o print.
Nota:
Se PHP è incorporato in XML o XHTML, devono essere utilizzati i normali tag PHP
<?php ?>per rimanere conformi agli standard.
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User Contributed Notes 4 notes
quickfur at quickfur dot ath dot cx ¶
14 years ago
ravenswd at gmail dot com ¶
15 years ago
One aspect of PHP that you need to be careful of, is that ?> will drop you out of PHP code and into HTML even if it appears inside a // comment. (This does not apply to /* */ comments.) This can lead to unexpected results. For example, take this line:
<?php
$file_contents = '<?php die(); ?>' . "\n";
?>
If you try to remove it by turning it into a comment, you get this:
<?php
// $file_contents = '<?php die(); ?>' . "\n";
?>
Which results in ' . "\n"; (and whatever is in the lines following it) to be output to your HTML page.
The cure is to either comment it out using /* */ tags, or re-write the line as:
<?php
$file_contents = '<' . '?php die(); ?' . '>' . "\n";
?>
sgurukrupa at gmail dot com ¶
10 years ago
Although not specifically pointed out in the main text, escaping from HTML also applies to other control statements:
<?php for ($i = 0; $i < 5; ++$i): ?>
Hello, there!
<?php endfor; ?>
When the above code snippet is executed we get the following output:
Hello, there!
Hello, there!
Hello, there!
Hello, there!
gazianis005 at gmail dot com ¶
1 year ago
There are two types of escaping from HTML.
1.Normal escaping of using outside of a pair of opening and closing tag
2.Advance escaping of using conditions.
Example of normal escaping
<p>This is going to be ignored by the php parser and displayed by the browser</p>
<?php echo 'This is going to be parsed';?>
<>This will also ignored by the php parser and displayed by the browser</>
Example of advanced escaping
<?php if($expression == true): ?>
This will show if expression is true
<?php else : ?>
Otherwise this will show
<?php endif ;?>
