PHP-具有\\ x7f-xff char的函数或类名称的示例

Question

PHP manual says that legal char set for class of function name is

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

And I m confused how to use \\x7f-\\xff as first char.

function 0x7ftest(){}

and

function \x7ftest(){}

raise execution errors.

Can someone make an example, plz?

Answer 1

\\x means that it is hex-encoded. \\x7F is the non-printable DEL character. Many of the characters in the [\\x7f-\\xff] range are non-printable, or are modifiers that are used with other characters to modify what they look like.

You can use this page to find the characters (in the The extended ASCII codes table, HEX column).

For example, you can use \\x8C (the Œ character), like this:

function Œ() {
    return "Πis a ligature of OE!";
}
echo Œ();

You should refrain from using these characters in your code because you cannot easily type them using most keyboards, and because most of them are non-printable (ie they do not appear on the screen as characters, or if they do they often appear as some "unknown" character: ?, or □).