Lets start at the beginning. Lets start with creating a blank PHP script. What's one of the most important things to remember when creating a new PHP script? I'll tell ya: Whitespace Matters!

You must keep track of your whitespace in PHP scripts. Why? HTTP headers cannot be set if you have already "printed" any characters. Stray spaces before and after segments will, among other things, prevent you from setting HTTP headers (e.g. session cookies, redirects, and so on).

This is something I run into over and over and over and over in modifying carelessly written code. Sometimes this is the work of a well intentioned developer trying to make code "more readable". Worse, this is a problem you won't catch until its too late. You can code for months or years on a project and never notice any problems. Until one day everything explodes for no obvious reason. There are huge, massive projects out there that still haven't completely learned this lesson.

Opening Demarcation
If your script contains only PHP code then it must begin with <?php at the very beginning of the file. No spaces. No new lines. <?php should be the very first characters in your new file. Don't use asptags <%, don't use shorttags <? or any other cutesy business.

Closing Demarcation
If your script contains only code and no embedded HTML markup then it must never include a ?> closing tag. Never. Ever. Yes, of course it'll work. Don't do it. Omitting the closing ?> ensures that all trailing whitespace will be in a code segment and not your output buffer.

Good Example

Bad Example

Labels: php, php102, web development