Characters

[cags]

This isn't exactly a Regular Expressions question, but since it's in relation to a pattern and I couldn't think of anywhere better to put it, it's going in the Regular Expressions section. The PHP manual defines valid user-defined function names as being...

 

[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*

 

Ok, fair enough, but what characters are \x7f-\xff? As far as my knowledge stretches \x is an escape character followed by a hex code of some kind. But they aren't any valid ASCII characters that I know of, so what encoding is it? I never did fully understand character encodings.

[rajivgonsalves]

I think that is ASCII 127 to 255 I think not too sure, but from what I understand this could be for special character in other languages which use different keyboards, however I am not to sure about this and could be completely wrong

[thebadbad]

rajiv is right, you can check the range in the last table on this page: http://www.ascii-code.com/

 

Edit: And you can output the range using range():

 

<?php
print_r(range("\x7f", "\xff"));
?>

[cags]

If that is the case, that doesn't make a whole deal of sense (to me at least). Since \x7f-\xff indicates all characters in that range, 7f is DELETE, &nbsp is also included in that range. I can perhaps understand some of the foreign characters being accepted but there are a lot of characters in that range that I really wouldn't expect to be valid. Having said that, I tested a few at random such as ¶ and they do appear to be valid.

[salathe]

Just for reference, the hex escape sequence for double quoted strings is mentioned in the manual in the strings section: http://php.net/types.string