PHP: Escapando o HTML

Escapando o HTML

Tudo fora de um par de tags de abertura e fechamento é ignorado pelo interpretador PHP, o que permite que arquivos PHP tenham conteúdo misto. Isso permite que o PHP seja incluído em documentos HTML, por exemplo, para criar templates.

<p>Isso será ignorado pelo PHP e exibido pelo navegador.</p>
<?php echo 'Enquanto isto vai ser interpretado.'; ?>
<p>Isso também será ignorado pelo PHP e exibido no navegador.</p>

Isso funcionará como esperado, porque quando o interpretador PHP encontra a tag de fechamento ?>, ele simplesmente começa a repassar o que quer que encontre (exceto a nova linha imediata, veja a seção sobre separação de instruções), até encontrar outra tag de abertura, a menos que esteja no meio de uma declaração condicional, caso em que o interpretador determinará o resultado da condicional antes de decidir qual caminho tomar. Veja o próximo exemplo.

Usando estruturas com condições

Exemplo #1 Escape avançado usando condições

<?php if ($expression == true): ?>
  Isso irá aparecer se a expressão for verdadeira.
<?php else: ?>
  Senão isso irá aparecer.
<?php endif; ?>

Neste exemplo, o PHP pulará os blocos onde a condição não for satisfeita, mesmo que os trechos de código estejam fora das tags de abertura e fechamento do PHP, pois o interpretador PHP pulará os blocos contidos em uma condição que não foi satisfeita.

Para imprimir grandes blocos de texto, sair do modo de interpretação do PHP é geralmente mais eficiente do que enviar todo o texto usando echo ou print.

Nota:
Se o PHP for incluído no XML ou XHTML, as tags normais <?php ?> devem ser usadas para manter a conformidade com os padrões.

＋add a note

User Contributed Notes 12 notes

down

384

quickfur at quickfur dot ath dot cx ¶

13 years ago

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!

down

ravenswd at gmail dot com ¶

14 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";
?>

down

gazianis005 at gmail dot com ¶

5 months 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 ;?>

down

snor_007 at hotmail dot com ¶

13 years ago

Playing around with different open and close tags I discovered you can actually mix different style open/close tags

some examples

<%
//your php code here
?>

or

<script language="php">
//php code here
%>

down

sgurukrupa at gmail dot com ¶

9 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!

down

-2

anisgazig at gmail dot com ¶

3 years ago

Version of  7.0.0,3 tags are available in php.
1.long form tag (<?php ?>)
2.short echo tag(<?= ?>)
3.short_open_tag(? ?)
You can use short_open_tag when you start xml with php.

down

-3

bryanrojasq.wordpress.com ¶

1 year ago

Example for a basic implementation of ternary operator to validate and print a class in the layout.

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title><?= $page_title ?></title>
</head>
<body <?= strtolower($page_slug) === 'homepage' ? 'class="page-homepage"' : ''; ?>>
    <section>
        <h1><?= $page_title ?></h1>
        <p>This is a paragraph.</p>
    </section>
</body>
</html>

down

-6

mike at clove dot com ¶

12 years ago

It's possible to write code to create php escapes which can be processed later by substituting \x3f for '?' - as in echo "<\x3fphp echo 'foo'; \x3f>";

This is useful for creating a template parser which later is rendered by PHP.

down

-23

davidhcefx ¶

3 years ago

When the PHP interpreter hits the ?> closing tags, it WON'T output right away if it's inside of a conditional statement:
(no matter if it's an Alternative Syntax or not)

<html>
<?php
$a = 1;
$b = 2;
if ($a === 1) {
    if ($b == 2) {
        ?><head></head><?php
    } else {
        ?><body></body><?php
    }
}
?>
</html>

This would output `<html><head></head></html>`.
Aside from conditional statements, the PHP interpreter also skip over functions! What a surprise!

<html>
<?php
function show($a) {
    ?>
    <a href="https://www.<?php echo $a ?>.com">
    Link
    </a>
    <?php
}
?>
<body>
    <?php show("google") ?>
</body>
</html>

This gives `<html><body><a href="https://www.google.com">Link</a></body></html>`.
These really confused me, because at first I thought it would output any HTML code right away, except for Alternative Syntaxes (https://www.php.net/manual/en/control-structures.alternative-syntax.php). There are more strange cases than I thought.

down

-19

Anonymous ¶

2 years ago

Since it's not documented (AFAICT) and it might cause confusion: a single line break immediately after ?> is ignored. Since whitespace is hard to see, whitespace is replaced with _ and the following code

<?php echo '1'; ?>
<?php echo '2'; ?>_
<?php echo '3'; ?>
_<?php echo '4'; ?>_<?php echo '5'; ?>

will produce

12_
3_4_5

down

-28

anisgazig.com ¶

3 years ago

<p>This is ignore by the php parser and displayed by the browser </p>

 <?php echo "While this is going to be parsed"; ?>

 <?php 

when php interpreter hits the closing tag it start to outputing everything whatever it finds until it hit another opening tag.If php interpreter find a conditional statement in the middle of a block then php interpreter decided which block skip  

 Advanced escaping using conditions

  <?php $a = 10; if($a<100): ?>
  This conditional block is executed
  <?php else: ?>
      otherwise this will be executed
      <?php endif; ?>

In php 5 version,there are 5 opening and closing tags.
1.<?php echo "standard long form php tag and if you use xml with php this tag will be use";?>

2.<?= "short echo tag and alwayes available from 5.4.0";?>

3.<? echo "short open tag which is available if short_open_tag is enable in php ini configuration file directive or php was configured with --enable-short-tags.This tag has discoursed from php 7.If you want to use xml with php,then short_open_tag in php ini will be disabled";?>

4.<script language="php">
echo "Some editor do not like processing the code within this tag and this tag is removed from php 7.0.0 version";

</script>

5.<% echo "asp style tag and asp_tags should be enabled but now php 7.0.0 version,this tag is removed";%>

down

-51

Emil Cataranciuc ¶

5 years ago

"<script language="php"> </script>, are always available." since PHP 7.0.0 is no longer true. These are removed along the ASP "<%, %>, <%=" tags.

＋add a note