Question

This might be a silly question but it struck me, and here i ask.

<?php
  $x="Hi";
  $y=" There";
  $z = $x.$y;
  $a = "$x$y";
  echo "$z"."<br />"."$a";
?>

$z uses the traditional concatenation operator provided by php and concatenates, conversely $a doesn’t,

My questions:

1. by not using the concatenation operator, does it effect the performance?

2. If it doesn’t why at all have the concatenation operator.

3. Why have 2 modes of implementation when one does the work?

Answer 1

1. Only slightly, since PHP has to parse the entire string looking for variables, while with concatenation, it just slaps the two variables together. So there’s a tiny performance hit, but it’s not noticeable for most things.

2. It’s a lot easier to concatenate variables like $_SERVER['DOCUMENT_ROOT'] using the concatenation operator (with quotes, you have to surround the variable in brackets or remove the single quotes in the array index; plus it just makes the string look all ugly). Plus, the concatenation operator allows more flexibility for formatting. For example, you can break up a long string literal onto multiple lines and then concatenate the different parts of it:

   $blah = "This is a really really long string. I don't even know how " .
       "long it is, but it's really long. Like, longer than an eel " .
       "or even a boa constrictor. Wow.";
   

   You can also use the concatenation operator to directly include return values from functions in a string literal (you can’t include a function call in a double-quoted string), like this:

   $blah = "This has a " . fn_call() . " result, which can't go in the quotes.";
   

3. I’m not sure I entirely understand what you’re asking here, but I can say that PHP borrows a lot of things from Perl, and one of Perl’s mantras is “There’s more than one way to do it.”