Why does ltrim remove one character too much?

Question

<?php
echo ltrim('12Hello World', '\x30..\x39');
echo "<br />";
echo ltrim('12Hello World', '0123456789');

Gives the output:

ello World
Hello World

Why? I understand that it is an array of characters and every character is stripped but if that's the case why is the H removed in the first case?

Answer 1

'\x30..\x39' is the following character mask:

• \
• x
• 3
• 0..\, i.e. anything from 0 through \, which includes H
• 9

You need to use double quotes, otherwise the \xXX escape sequences aren't interpreted as bytes:

"\x30..\x39"

That's the character mask for anything from byte x30 through x39, which is 0 - 9 in ASCII and compatible encodings.

Answer 2

Escape sequences aren't interpreted inside single quotes. So your second argument is interpreted literally. It says to trim the following characters:

• \
• x
• 3
• 0 through \
• x
• 3
• 9

If you take a look at an ASCII chart, you'll see that the range 0 through \ includes all the uppercase letters.

Change to a double-quoted string to have the hex escape sequence interpreted:

echo ltrim("12Hello World", "\x30..\x39")

produces:

Hello World