Strange PHP syntax

Question 1

I've been working on PHP for some time but today when I saw this it came as new to me:

if(preg_match('/foo.*bar/','foo is a bar')):
        echo 'success ';
        echo 'foo comes before bar';

endif;

To my surprise it also runs without error. Can anyone enlighten me?

Thanks to all :)

Question 2

That style of syntax is more commonly used when embedding in HTML, especially for template/display logic. When embedded this way, it's a little easier to read than the curly braces syntax.

<div>
<? if ($condition): ?>
  <ul>
    <? foreach($foo as $bar): ?>
        <li><?= $bar ?></li>
    <? endforeach ?>
  </ul>
<? endif ?>
</div>

Versus:

<div>
<? if ($condition) { ?>
  <ul>
    <? foreach($foo as $bar) { ?>
      <li><?= $bar ?></li>
    <? } ?>
  </ul>
<? } ?>

The verbose end tags make it a little easier to keep track of nested code blocks, although it's still mostly personal preference.

Question 3

${ } (dollar sign curly bracket) is known as Simple syntax.

It provides a way to embed a variable, an array value, or an object property in a string with a minimum of effort.

If a dollar sign ($) is encountered, the parser will greedily take as many tokens as possible to form a valid variable name. Enclose the variable name in curly braces to explicitly specify the end of the name.
<?php
$juice = "apple";

echo "He drank some $juice juice.".PHP_EOL;
// Invalid. "s" is a valid character for a variable name, but the variable is $juice.
echo "He drank some juice made of $juices.";
// Valid. Explicitly specify the end of the variable name by enclosing it in braces:
echo "He drank some juice made of ${juice}s.";
?>
The above example will output:
He drank some apple juice.
He drank some juice made of .
He drank some juice made of apples.

Question 4

global is a keyword that should be used by itself. It must not be combined with an assignment. So, chop it:

global $x;
$x = 42;

Also, as Zenham mentions, global is used inside functions, to access variables in an outer scope. So the use of global as it is presented makes little sense.

Another tip (though it will not really help you with syntax errors): add the following line to the top of the main file, to help debugging (documentation):

error_reporting(E_ALL);

Question 5

I use this kind of pattern often. It's very compact:

// Define a constant in your class. Use a HashSet for performance
private static final Set<Integer> values = new HashSet<Integer>(Arrays.asList(12, 16, 19));

// In your method:
if (values.contains(x)) {
    ...
}

A HashSet is used here to give good look-up performance - even very large hash sets are able to execute contains() extremely quickly.

If performance is not important, you can code the gist of it into one line:

if (Arrays.asList(12, 16, 19).contains(x))

but know that it will create a new ArrayList every time it executes.

Question 6

How about

for r in [regex.match(s) for s in str]:
    if r:
        print r.groups()

or a bit more functional

for r in filter(None, map(regex.match, str)):
    print r.groups()

Strange PHP syntax

Answers

php,syntax,if-statement,alternate,control-structure