3
I also commonly see it in header() function calls. And now I understand...
It _is_ a PHP thing I don't know about. I found this at
http://us2.php.net/language.types.stringHope it helps someone else trying to wade into this.
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Complex (curly) syntaxThis isn't called complex because the syntax is complex, but because you can include complex expressions this way.
In fact, you can include any value that is in the namespace in strings with this syntax. You simply write the expression the same way as you would outside the string, and then include it in { and }. Since you can't escape '{', this syntax will only be recognised when the $ is immediately following the {. (Use "{\$" or "\{$" to get a literal "{$"). Some examples to make it clear:
<?php
// Let's show all errors
error_reporting(E_ALL);
$great = 'fantastic';
// Won't work, outputs: This is { fantastic}
echo "This is { $great}";
// Works, outputs: This is fantastic
echo "This is {$great}";
echo "This is ${great}";
// Works
echo "This square is {$square->width}00 centimeters broad.";
// Works
echo "This works: {$arr[4][3]}";
// This is wrong for the same reason as $foo[bar] is wrong
// outside a string. In other words, it will still work but
// because PHP first looks for a constant named foo, it will
// throw an error of level E_NOTICE (undefined constant).
echo "This is wrong: {$arr[foo][3]}";
// Works. When using multi-dimensional arrays, always use
// braces around arrays when inside of strings
echo "This works: {$arr['foo'][3]}";
// Works.
echo "This works: " . $arr['foo'][3];
echo "You can even write {$obj->values[3]->name}";
echo "This is the value of the var named $name: {${$name}}";
?>
