August 29, 2008 11:50pm pdt

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	[x] Attachment Details

PHP PCRE Regex or str_replace for Hex Characters "0D-0A 0C 0D 0A"

Zones: Regular Expressions, Miscellaneous Programming, PHP Scripting Language

Tags: hex, 0d, 0a, php

I have hundreds of TXT files, in ASCII format, that have a lots of page-breaks that I want to remove or replace.
When I look at it in Windows Notepad, it just looks like a little vertical rectangle on its own line. As best I can tell from a hex viewer, the hex characters for this page-break are:
0D-0A 0C 0D 0A

I know how to do PCRE regex for a single hex character like
$string = preg_replace('/\x0A/', '\n', $string);
but I would prefer to do a full-replace of the whole page-break code (for example, to replace the whole thing with an empty string).
I don't know how to handle a hyphenated code e.g. "0D-0A" or a whole string of codes like 0D-0A 0C 0D 0A .

And because str_replace is faster than preg_replace, I hope there's a way to do it with str_replace.
Please advise.

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9.2

Question Stats

Zone: Programming

Question Asked By: FrankTech

Solution Provided By: ozo

Participating Experts: 3

Solution Grade: A

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Comment by b0lsc0tt

FrankTech,

If the suggestion above doesn't work or isn't enough could you upload a small sample of the text with those characters. You can zip the file and upload the zip file to www.ee-stuff.com , a site just for EE members. Let me know if you have a question or need more info on this. What is the hex viewer you used?

Most likely you will need to use a PHP function that will support an expression. I don't believe str_replace will.

Let me know if you have any questions or need more information.

b0lsc0tt

Comment by b0lsc0tt

Oops, should've refreshed. I left my browser too long. :) Good job Ozo!

bol

Comment by FrankTech

b0lsc0tt,
Thanks. I discovered that str_replace _does_ work for single hex characters if I use double quotes, like this:
$text = str_replace("\x0A", "", $text);
OR with combinations of single characters, like this:
$text = str_replace("\x0A\x0C\x0D", "", $text);

but I couldn't get it to work with the hyphated character \x0A-\x0D . I wish it could, because that would be faster than preg_replace.

Comment by b0lsc0tt

Yes, I didn't think of that possibility. That isn't really an expression still but is very helpful to remember. In a string that uses double quotes PHP will understand a number of "special characters." As you found out the \xHH is used for characters with a hex reference. Since the hexadecimal reference only allows 1 or 2 characters the hypenated one would have a problem. I am actually still curious as to what that charact is if it really is a single character. Oh, well. :)

If you are curious there is info on the other characters at http://us.php.net/manual/en/language.types.string.php#language.types.string.syntax.double .

bol

Comment by ddrudik

FrankTech, note that the construct "[\x0A-\x0D]" is the same as either "[\x0A\x0B\x0C\x0D]" or "(\x0A|\x0B|\x0C|\x0D)". Normally a page break in a text file would be represented as the sequence "\x0C\x0D\x0A", the "\x0D\x0A" you saw prior to the page break was likely a CRLF sequence.

20080723-EE-VQP-34 / EE_QW_2_20070628