流程控制的替代语法 ¶
(PHP 4, PHP 5, PHP 7)
PHP 提供了一些流程控制的替代语法，包括 if，while，for，foreach 和 switch。替代语法的基本形式是把左花括号（{）换成冒号（:），把右花括号（}）分别换成 endif;，endwhile;，endfor;，endforeach; 以及 endswitch;。
<?php if ($a == 5): ?>
A is equal to 5
<?php endif; ?>在上面的例子中，HTML 内容“A is equal to 5”用替代语法嵌套在 if 语句中。该 HTML 的内容仅在 $a 等于 5 时显示。
替代语法同样可以用在 else 和 elseif 中。下面是一个包括 elseif 和 else 的 if 结构用替代语法格式写的例子：
<?php
if ($a == 5):
echo "a equals 5";
echo "...";
elseif ($a == 6):
echo "a equals 6";
echo "!!!";
else:
echo "a is neither 5 nor 6";
endif;
?>Note:
不支持在同一个控制块内混合使用两种语法。
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User Contributed Notes 7 notes
flyingmana ¶
7 years ago
It seems to me, that many people think that
<?php if ($a == 5): ?>
A ist gleich 5
<?php endif; ?>
is only with alternate syntax possible, but
<?php if ($a == 5){ ?>
A ist gleich 5
<?php }; ?>
is also possible.
alternate syntax makes the code only clearer and easyer to read
temec987 at gmail dot com ¶
5 years ago
A simple alternative to an if statement, which is almost like a ternary operator, is the use of AND. Consider the following:
<?php
$value = 'Jesus';
// This is a simple if statement
if( isset( $value ) )
{
print $value;
}
print '<br />';
// This is an alternative
isset( $value ) AND print( $value );
?>
This does not work with echo() for some reason. I find this extremely useful!
v14t at gmx dot com ¶
2 years ago
isset( $value ) AND print( $value );
the reason why it doesn't work with echo, it's because echo does not return anything, while print _always_ returns 1, which is considered true in the expression
jeremia at gmx dot at ¶
8 years ago
If you wan't to use the alternative syntax for switch statements this won't work:
<div>
<?php switch($variable): ?>
<?php case 1: ?>
<div>
Newspage
</div>
<?php break;?>
<?php case 2: ?>
</div>
Forum
<div>
<?php break;?>
<?php endswitch;?>
</div>
Instead you have to workaround like this:
<div>
<?php switch($variable):
case 1: ?>
<div>
Newspage
</div>
<?php break;?>
<?php case 2: ?>
</div>
Forum
<div>
<?php break;?>
<?php endswitch;?>
</div>
timeroot dot alex at gmail dot com ¶
2 years ago
The reason for the "workaround" jeremiah mentioned, in the case of the switch statement, can be understood as follows; in any place where you can have an echo statement (an if block, a switch's case, whatever), that's where you can have the raw HTML. In PHP this basically gets handled just like that -- like an echo statement.
In between a switch and a case, though, you can't echo anything. By placing the switch and the case in two separate blocks of PHP, with a raw HTML newline echo'ed in between them, PHP basically had to try to find where that statement would be. And it can't be there, hence the difficulty.
skippy at zuavra dot net ¶
11 years ago
If it needs saying, this alternative syntax is excellent for improving legibility (for both PHP and HTML!) in situations where you have a mix of them.
Interface templates are very often in need of this, especially since the PHP code in them is usually written by one person (who is more of a programmer) and the HTML gets modified by another person (who is more of a web designer). Clear separation in such cases is extremely useful.
See the default templates that come with WordPress 1.5+ (www.wordpress.org) for practical and smart examples of this alternative syntax.
josh at qaribou dot com ¶
2 years ago
The reason temec987's approach of using boolean operators as an alternative to control structures won't work for an 'echo' is because the result of evaluating the expression will always be a boolean.
Other languages (e.g. ruby) are much better suited to this approach, as the expression evaluated will be the resultant value, e.g.:
5 && 4
In ruby, this would be 4, but in PHP, this would be true (type-juggled equivalent is 1), which isn't useful for anything but further binary logic.
You can still use logical operators as conditionals, but only for executing logic, not for getting a value back, e.g.:
<?php
defined('USER_CAN_EXECUTE') or die('Access denied.');
?>
is a nice one to use for access control, or say you want to put in a quick check that your object has all the data loaded it needs to call a webservice (functions are just examples):
<?php
$this->readyForService() and $this->postData('http://endpoint.com');
?>
What you can't use them for is something like this:
<?php
echo (strlen($mystring) > 5) and $mystring;
?>
instead, you'd use ternaries for that:
<?php
echo (strlen($mystring) > 5) ? $mystring : null;
?>