Variable parsing: Complex (curly) syntax
<?php
// 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}";
// Works
echo "This square is {$square->width}00 centimeters broad.";
// Works, quoted keys only work using the curly brace syntax
echo "This works: {$arr['key']}";
// Works
echo "This works: {$arr[4][3]}";
// This is wrong for the same reason as $foo[bar] is wrong outside a string.
// In other words, it will still work, but only because PHP first looks for a
// constant named foo; an error of level E_NOTICE (undefined constant) will be
// thrown.
echo "This is wrong: {$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: " . $arr['foo'][3];
echo "This works too: {$obj->values[3]->name}";
echo "This is the value of the var named $name: {${$name}}";
echo "This is the value of the var named by the return value of getName(): {${getName()}}";
echo "This is the value of the var named by the return value of \$object->getName(): {${$object->getName()}}";
// Won't work, outputs: This is the return value of getName(): {getName()}
echo "This is the return value of getName(): {getName()}";
?>
<?php
class foo {
var $bar = 'I am bar.';
}
$foo = new foo();
$bar = 'bar';
$baz = array('foo', 'bar', 'baz', 'quux');
echo "{$foo->$bar}\n";
echo "{$foo->{$baz[1]}}\n";
?>
<?php
// Show all errors.
error_reporting(E_ALL);
class beers {
const softdrink = 'rootbeer';
public static $ale = 'ipa';
}
$rootbeer = 'A & W';
$ipa = 'Alexander Keith\'s';
// This works; outputs: I'd like an A & W
echo "I'd like an {${beers::softdrink}}\n";
// This works too; outputs: I'd like an Alexander Keith's
echo "I'd like an {${beers::$ale}}\n";
?>
- Any scalar variable, array element or object property with a string representation can be included via this syntax.
- Simply write the expression the same way as it would appear outside the string, and then wrap it in { and }.
- Since { can not be escaped, this syntax will only be recognised when the $ immediately follows the {. Use {\$ to get a literal {$.
This isn't called complex because the syntax is complex, but because it allows for the use of complex expressions.
Related concepts
→
Complex (curly) syntax