Did you test it, looks like you got it!
How to test (the script won't run until all stuff is fixed, I know: ) You pull out a piece and put it in a test file, like
<?php
$fileName = 'testme/';
if (preg_match('|^[^./][^/]*$|', $fileName)) { echo "works"; }
else { echo "Fails"; }
?>
I'm not sure what this particular code does
The basics of regular expression pattern matching is delimiter-pattern-delimiter-modifiers. Using the previous:
' = this is the
PHP delimiter for the pattern - it has nothing to do with regular expressions, it's just how you use PHP's preg functions. Completely equivalent would be
"|^[^./][^/]*$|"
| = This is the opening delimiter for the regex. A delimiter can be ANYTHING, so long as it's not one of the characters you're matching on (or, you escape that character within the regex.) The "usual" delimiters are /, but they used the pipe | because / is part of the pattern, and they didn't want to escape it. All of these are exactly the same as your original.
'/^[^.\/][^\/]*$/' (escaped)
'-^[^./][^/]*$-'
'_^[^./][^/]*$_'
Because metacharacters (- ^ | $ !, etc.) are very important in regex's depending on the context (WHERE you use them), this can get very confusing very fast. :-) the dash -, for example, when used within a character class means a range. ([a-z] = letters a to z.)
^ = This is one of those cases of context. When the first character in a pattern, it means "the string I'm checking the pattern against starts with." Within a
character class, it is a negation operator (below.)
[] = The brackets create a class, that is, normally, "match on all of these characters."
[^./] Since the first character in the class is the carat, in this context it means, "anything NOT these characters." Because it "stands alone" without a
quantifier, is also means "one and ONLY one of these." So all together,
[^./] means "one and only one of either a dot or a /"
Some examples of quantifiers beyond "one and only one,"
[^./]+ = One or more of either a dot or a slash
[^./]? = Zero or one of either a dot or a slash
[^./]* = Zero or any number of of either a dot or a slash
[^./]{1,3} = no less than one or no more than 3 of either a dot or a slash
The dot character is another contextual "gotcha" - outside of a class, it means "zero or more of any character." Inside a character class like that, it's just a character, the dot.
[^/]* = You probably got it from the previous - following the first part, it's followed by zero or more of anything NOT a /.
$ = Like a bare ^ at the beginning, this means "The string I'm checking the pattern against ends here."
| = End of the pattern
Modifiers: After the pattern delimiter and before the ending PHP string delimiter you may have modifiers, which tell the engine how to manage the match - for example, "i" is "treat it as case-insensitive." You can see the modifier in your second one,
!preg_match("/" . basename($_SERVER['PHP_SELF']) . "/i", $fileName)
For example, if you're trying to match on the word "file," it will match either FILE or file or fIlE, regexes are not case-insensitive by default.
' = PHP Ending of the pattern match string.
All together, '|^[^./][^/]*$|' means
Match on a string that starts with one or more characters that are NOT a dot or a slash and ends with zero or more characters that are not a slash.
