Why is PHP changing the first character after ltrim or str_replace?

Question

I'm trying to remove a part of a directory with PHPs ltrim(), however the result is unexpected. The first letter of my result has the wrong ascii value, and shows up as missing character/box in the browser.

Here is my code:

$stripPath = "public\docroot\4300-4399\computer-system-upgrade";
$directory = "public\docroot\4300-4399\computer-system-upgrade\3.0 Outgoing Documents";

$shortpath = ltrim($directory, $stripPath);
echo $shortpath;

Expected output:

3.0 Outgoing Documents

Actual output:

.0 Outgoing Documents

Note the invisible/non-print character before the dot. Ascii value changed from Hex 33 (the number 3) to Hex 03 (invisible character). I also tried str_replace() instead of trim(), but the result stays the same.

What am i doing wrong here? How would i get the expected result "3.0 Outgoing Documents"?

Answer 1

When you provide a string value in quotation marks you have to be aware that the backslash is used as a masking character. So, \\3 is understood as the ASCII(3) character. In your example you need to provide double backslashes in order to define your desired string (having single backslashes in it):

$stripPath = "public\\docroot\\4300-4399\\computer-system-upgrade\\";
$directory = "public\\docroot\\4300-4399\\computer-system-upgrade\\3.0 Outgoing Documents";

Answer 2

Backslash is PHP's escape sequence. Add a backslash to 'stripPath' to trim it from 'dirctory'

Answer 3

Don't use ltrim.
Ltrim does not replace straight off. It strips kind of like regex does.
Meaning all characters you put in the second argument is used to remove anything.
See example: https://3v4l.org/AfsHJ
The reason it stops at . is because it's not part of $stripPath

You should instead do is use real regex or simple str_replace.

$stripPath = "public\docroot\4300-4399\computer-system-upgrade";
$directory = "public\docroot\4300-4399\computer-system-upgrade\3.0 Outgoing Documents";

 $shortpath = str_replace($stripPath, "", $directory);
 echo $shortpath;

https://3v4l.org/KF2Iv

Answer 4

That happens because of / mark because / has a special meaning.

If you try this with a space you can get the expected output.

$stripPath = "public\docroot\4300-4399\computer-system-upgrade";
$directory = "public\docroot\4300-4399\computer-system-upgrade 3.0 Outgoing Documents";

$shortpath = ltrim($directory, $stripPath);
echo $shortpath;