What is x7f in php?

Question

What is x7f and xff in php?

Is it hexa or octal?

EDIT:

The PHP 5.3 manual states that as a regular expression, the class name will be expressed as: [a-zA-Z_ \ x7f- \ xff] [a-zA-Z0-9_ \ x7f- \ XFF] * .

can anyone help what is the meaning of \ x7f- \ xff in the correct expression?

Answer 1

According to the whole page on PHP.net, the hex format in PHP:

hexadecimal : 0[xX][0-9a-fA-F]+ 

therefore it will be hexadecimal.

Answer 2

Like others, its x7f and xff are hexadecimal code that matches the extended ASCII characters that can be added as part of the class name in php. ASCII Codes

Answer 3

The prefix 0x (not just x ) means hexadecimal, so 0x7f is 127, and 0xff is 255.