PHP File Formatting
Tags
PHP code must always being with the long form opening tag. If a file contains only PHP code, the end tag may optionally be omitted from the end of the file.
<?php ?>
Indentation
Tabs should always be used for indentation. Spaces should never be used for indentation. We live in a world where IDEs can be configured to display tabs at variable lengths, so configure your tab width to what you feel comfortable with.
Line Length
Lines should be designed such that a reader can avoid horizontal scrolling, except in cases where scrolling offers improved readability over word-wrapping. As the resolution and width of monitors has increased the standard with of 80 characters (previously the width of a punch card) no longer holds any relevance. Use your best judgement to determine where lines should wrap.
EOL
Every line should terminate with a line-feed (LF) character only. That is '\n', also known as hex value 0x0A. Do not use CRLF (Window systems) or CR (Mac systems).
Character Encoding
All PHP files should be encoded using UTF-8, with no byte-order-mark (BOM).
Programming Styles
Strings
Literals
Strings consisting of more than one character should be surrounded with double-quotes ("). Strings consisting of only a single character may be surrounded with single-quotes (').
$str = "This is a long string"; $chr = 'a';
Concatenation
Run-on Strings
A string whose length requires it to wrap multiple lines should be concatenated with the concatenation character (.) appended at the end of the line, with the carry-over line indented below it.
$str = "This is a string that needs to " . "wrap onto another line.";
Variable Substitution
When a variable needs to be added to a string the string should be broken open and concatenated together to improve readability.
$name = "Hefo Quient Esbit"; $str = "Hello " . $name . "! How are you?"