echo "Your IP address is {$_SERVER['REMOTE_ADDR']}";

Why were those curly brackets in the echo statement and why wasn’t this giving me errors? I removed the curly brackets and as expected, I received syntax errors. Apparently the {} were magical. Now in my own code, I would typically write the above line like:

echo "Your IP address is " . $_SERVER['REMOTE_ADDR'];

or

echo "Your IP address is $_SERVER[REMOTE_ADDR]";

Now method one is perfectly valid code, but it’s a bit ugly having to starty and stop the string to insert a variable. Method 2 is somewhat wrong as the quotes have been removed from the server array key.  According to php.net, “Always use quotes around a string literal array index. For example, $foo['bar'] is correct, while $foo[bar] is not.” But with this new, more compact method, I could make my code cleaner.  I was off to learn more.

After some searching I discovered that PHP will allow you to place curly brackets around a variable in a string (either around the entire variable or with the dollar sign sticking out). “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. Similarly, an array index or an object property can be parsed. With array indices, the closing square bracket (]) marks the end of the index. The same rules apply to object properties as to simple variables. ” Who knew? I must’ve missed this day during PHP 101 class. Here’s the example from the manual:

<?php
$beer = 'Heineken';
echo "$beer's taste is great"; // works; "'" is an invalid character for variable names
echo "He drank some $beers";   // won't work; 's' is a valid character for variable names but the variable is "$beer"
echo "He drank some ${beer}s"; // works
echo "He drank some {$beer}s"; // works
?>

So in a nushell, when using variables in a string you are allowed to enclose the varable in curly brackets to allow variable expansion without having to jump in and out of quotes, or drop quotes. Who doesn’t love PHP?