I want to use preg_replace to remove all unicode characters including Persian characters from a string and keep English and all special characters. The way I know to do it is :
preg_replace('/[^<>()/\* a-zA-Z0-9_.-]/u', '', $string);
But, I don't really want to include all special characters inside []. Is there any shorter way?!
To remove everything but characters falling in the basic ASCII range, you may use a pattern similar to this to match the range by HEX codes.
// Given a string with characters in and outside ASCII:
$s = "abcde啅cde衸xtzሴbb()*&bԴ";
// Match HEX 00-7F and remove characters outside that
// by inverting with ^
echo preg_replace('/[^\x00-\x7f]/', '', $s);
// Prints:
// abcdecdextzbb()*&b
Using HEX 00-7F will also include the start of the ASCII range, therefore covering things like NUL, terminal bell, backspace, etc. You may consider starting with ASCII 32 (hex 20) at SPACE if you don't want your output to include those special non-printable control characters.
echo preg_replace('/[^\x20-\x7f]/', '', $s);
My software uses the following before performing a search on a mySQL database:
$keywords_search = preg_replace("/[^a-zA-Z0-9 ]/", "", $keywords_search);
The problem is that it's stripping out words that users may use in other languages, like "españa" (spanish) due to the "ñ" character which is very common.
Is there any way to allow certain special characters in preg_replace?
If you want to make sure your keyword does not contain any malicious code, that's not a way to go, you should read this:
How can I prevent sql injection in php
If you just want to filter your search phrase, you can use the \p{L} pattern to match any letter and \p{N} to much any numeric character. Also you should use u modifier like this: /\p{L}+/u
Also be sure to check this question:
Regular expression \p{L} and \p{N}
You can try with this one
$keywords_search = preg_replace("/[^\w-\p{L}\p{N}\p{Pd}]/", "", $keywords_search);
This will match anything that's NOT an alphanumeric character (including UTF-8 letters) as well as the dash (-).
$html=strip_tags($html);
$html=ereg_replace("[^A-Za-zäÄÜüÖö]"," ",$html);
$words = preg_split("/[\s,]+/", $html);
doesnt this replace all non (A-Z, a-z, a o u with umlauts) characters with space?
I am losing words like zugänglich etc with umlauts
is there any thing wrong with the regex?
edit:
I replaced ereg_replace with preg_replace but somehow the special characters like :, ® are not getting replace by space...
If you succeed with your approach foremost depends on the encoding. When all umlauts got stripped, it's likely that your source text (or php script) was encoded as UTF-8.
In this case rather use:
$text = preg_replace('/[^\p{L}]/u', " ", $text);
This will match all letter characters, not just umlauts. And /u solves your likely charset problem.
Maybe, your umlauts are still html-entities (ä etc.) which contain non alphanumeric characters, that would be deleted...
BTW: Alphanumeric isn't just a-Z but numbers as well...
the regex should be /[^A-Za-zäÄÜüÖö]+/
How can I remove control characters like STX from a PHP string? I played around with
preg_replace("/[^a-zA-Z0-9 .\-_;!:?äÄöÖüÜß<>='\"]/","",$pString)
but found that it removed way to much. Is there a way to remove only
control chars?
If you mean by control characters the first 32 ascii characters and \x7F (that includes the carriage return, etc!), then this will work:
preg_replace('/[\x00-\x1F\x7F]/', '', $input);
(Note the single quotes: with double quotes the use of \x00 causes a parse error, somehow.)
The line feed and carriage return (often written \r and \n) may be saved from removal like so:
preg_replace('/[\x00-\x09\x0B\x0C\x0E-\x1F\x7F]/', '', $input);
I must say that I think Bobby's answer is better, in the sense that [:cntrl:] better conveys what the code does than [\x00-\x1F\x7F].
WARNING: ereg_replace is deprecated in PHP >= 5.3.0 and removed in PHP >= 7.0.0!, please use preg_replace instead of ereg_replace:
preg_replace('/[[:cntrl:]]/', '', $input);
For Unicode input, this will remove all control characters, unassigned, private use, formatting and surrogate code points (that are not also space characters, such as tab, new line) from your input text. I use this to remove all non-printable characters from my input.
<?php
$clean = preg_replace('/[^\PC\s]/u', '', $input);
for more info on \p{C} see http://www.regular-expressions.info/unicode.html#category
PHP does support POSIX-Classes so you can use [:cntrl:] instead of some fancy character-magic-stuff:
ereg_replace("[:cntrl:]", "", $pString);
Edit:
A extra pair of square brackets might be needed in 5.3.
ereg_replace("[[:cntrl:]]", "", $pString);
TLDR Answer
Use this Regex...
/[^\PCc^\PCn^\PCs]/u
Like this...
$text = preg_replace('/[^\PCc^\PCn^\PCs]/u', '', $text);
TLDR Explanation
^\PCc : Do not match control characters.
^\PCn : Do not match unassigned characters.
^\PCs : Do not match UTF-8-invalid characters.
Working Demo
Simple demo to demonstrate: IDEOne Demo
$text = "\u{0019}hello";
print($text . "\n\n");
$text = preg_replace('/[^\PCc^\PCn^\PCs]/u', '', $text);
print($text);
Output:
(-Broken-Character)hello
hello
Alternatives
^\PC : Match only visible characters. Do not match any invisible characters.
^\PCc : Match only non-control characters. Do not match any control characters.
^\PCc^\PCn : Match only non-control characters that have been assigned. Do not match any control or unassigned characters.
^\PCc^\PCn^\PCs : Match only non-control characters that have been assigned and are UTF-8 valid. Do not match any control, unassigned, or UTF-8-invalid characters.
^\PCc^\PCn^\PCs^\PCf : Match only non-control, non-formatting characters that have been assigned and are UTF-8 valid. Do not match any control, unassigned, formatting, or UTF-8-invalid characters.
Source and Explanation
Take a look at the Unicode Character Properties available that can be used to test within a regex. You should be able to use these regexes in Microsoft .NET, JavaScript, Python, Java, PHP, Ruby, Perl, Golang, and even Adobe. Knowing Unicode character classes is very transferable knowledge, so I recommend using it!
This regex will match anything visible, given in both its short-hand and long-hand form...
\PL\PM\PN\PP\PS\PZ
\PLetter\PMark\PNumber\PPunctuation\PSymbol\PSeparator
Normally, \p indicates that it's something we want to match and we use \P (capitalized) to indicate something that does not match. But PHP doesn't have this functionality, so we need to use ^ in the regex to do a manual negation.
A simpler regex then would be ^\PC, but this might be too restrictive in deleting invisible formatting. You may want to look closely and see what's best, but one of the alternatives should fit your needs.
All Matchable Unicode Character Sets
If you want to know any other character sets available, check out regular-expressions.info...
\PL or \PLetter: any kind of letter from any language.
\PLl or \PLowercase_Letter: a lowercase letter that has an uppercase variant.
\PLu or \PUppercase_Letter: an uppercase letter that has a lowercase variant.
\PLt or \PTitlecase_Letter: a letter that appears at the start of a word when only the first letter of the word is capitalized.
\PL& or \PCased_Letter: a letter that exists in lowercase and uppercase variants (combination of Ll, Lu and Lt).
\PLm or \PModifier_Letter: a special character that is used like a letter.
\PLo or \POther_Letter: a letter or ideograph that does not have lowercase and uppercase
\PM or \PMark: a character intended to be combined with another character (e.g. accents, umlauts, enclosing boxes, etc.).
\PMn or \PNon_Spacing_Mark: a character intended to be combined with another
character without taking up extra space (e.g. accents, umlauts, etc.).
\PMc or \PSpacing_Combining_Mark: a character intended to be combined with another character that takes up extra space (vowel signs in many Eastern languages).
\PMe or \PEnclosing_Mark: a character that encloses the character it is combined with (circle, square, keycap, etc.).
\PZ or \PSeparator: any kind of whitespace or invisible separator.
\PZs or \PSpace_Separator: a whitespace character that is invisible, but does take up space.
\PZl or \PLine_Separator: line separator character U+2028.
\PZp or \PParagraph_Separator: paragraph separator character U+2029.
\PS or \PSymbol: math symbols, currency signs, dingbats, box-drawing characters, etc.
\PSm or \PMath_Symbol: any mathematical symbol.
\PSc or \PCurrency_Symbol: any currency sign.
\PSk or \PModifier_Symbol: a combining character (mark) as a full character on its own.
\PSo or \POther_Symbol: various symbols that are not math symbols, currency signs, or combining characters.
\PN or \PNumber: any kind of numeric character in any script.
\PNd or \PDecimal_Digit_Number: a digit zero through nine in any script except ideographic scripts.
\PNl or \PLetter_Number: a number that looks like a letter, such as a Roman numeral.
\PNo or \POther_Number: a superscript or subscript digit, or a number that is not a digit 0–9 (excluding numbers from ideographic scripts).
\PP or \PPunctuation: any kind of punctuation character.
\PPd or \PDash_Punctuation: any kind of hyphen or dash.
\PPs or \POpen_Punctuation: any kind of opening bracket.
\PPe or \PClose_Punctuation: any kind of closing bracket.
\PPi or \PInitial_Punctuation: any kind of opening quote.
\PPf or \PFinal_Punctuation: any kind of closing quote.
\PPc or \PConnector_Punctuation: a punctuation character such as an underscore that connects words.
\PPo or \POther_Punctuation: any kind of punctuation character that is not a dash, bracket, quote or connector.
\PC or \POther: invisible control characters and unused code points.
\PCc or \PControl: an ASCII or Latin-1 control character: 0x00–0x1F and 0x7F–0x9F.
\PCf or \PFormat: invisible formatting indicator.
\PCo or \PPrivate_Use: any code point reserved for private use.
\PCs or \PSurrogate: one half of a surrogate pair in UTF-16 encoding.
\PCn or \PUnassigned: any code point to which no character has been assigned.
To keep the control characters but make them compatible for JSON, I had to to
$str = preg_replace(
array(
'/\x00/', '/\x01/', '/\x02/', '/\x03/', '/\x04/',
'/\x05/', '/\x06/', '/\x07/', '/\x08/', '/\x09/', '/\x0A/',
'/\x0B/','/\x0C/','/\x0D/', '/\x0E/', '/\x0F/', '/\x10/', '/\x11/',
'/\x12/','/\x13/','/\x14/','/\x15/', '/\x16/', '/\x17/', '/\x18/',
'/\x19/','/\x1A/','/\x1B/','/\x1C/','/\x1D/', '/\x1E/', '/\x1F/'
),
array(
"\u0000", "\u0001", "\u0002", "\u0003", "\u0004",
"\u0005", "\u0006", "\u0007", "\u0008", "\u0009", "\u000A",
"\u000B", "\u000C", "\u000D", "\u000E", "\u000F", "\u0010", "\u0011",
"\u0012", "\u0013", "\u0014", "\u0015", "\u0016", "\u0017", "\u0018",
"\u0019", "\u001A", "\u001B", "\u001C", "\u001D", "\u001E", "\u001F"
),
$str
);
(The JSON rules state: “All Unicode characters may be placed within the quotation marks except for the characters that must be escaped: quotation mark, reverse solidus, and the control characters (U+0000 through U+001F).”)
regex free method
If you are only zapping the control characters I'm familiar with (those under 32 and 127), try this out:
for($control = 0; $control < 32; $control++) {
$pString = str_replace(chr($control), "", $pString;
}
$pString = str_replace(chr(127), "", $pString;
The loop gets rid of all but DEL, which we just add to the end.
I'm thinking this will be a lot less stressful on you and the script then dealing with regex and the regex library.
Updated regex free method
Just for kicks, I came up with another way to do it. This one does it using an array of control characters:
$ctrls = range(chr(0), chr(31));
$ctrls[] = chr(127);
$clean_string = str_replace($ctrls, "", $string);
I've got a bunch of data which could be mixed characters, special characters, and 'accent' characters, etc.
I've been using php inconv with translit, but noticed today that a bullet point gets converted to 'bull'. I don't know what other characters like this don't get converted or deleted.
$, *, %, etc do get removed.
Basically what I'm trying to do is keep letters, but remove just the 'non-language' bits.
This is the code I've been using
$slugIt = #iconv('UTF-8', 'ASCII//TRANSLIT', $slugIt);
$slugIt = preg_replace("/[^a-zA-Z0-9 -]/", "", $slugIt);
of course, if I move the preg_replace to be above the inconv function, the accent characters will be removed before they are translated, so that doesn't work either.
Any ideas on this? or what non-letter characters are missed in the TRANSLIT?
---------------------Edited---------------------------------
Strangely, it doesn't appear to be the TRANSLIT which is changing a bullet to 'bull'. I commented out the preg-replace, and the 'bull' has been returned to a bullet point. Unfortunately I'm trying to use this to create readable urls, as well as a few other things, so I would still need to do url encoding.
Try adding the /u modifier to preg_replace.
See Pattern Modifers
you can try using the POSIX Regex:
$slugIt = ereg_replace('[^[:alnum:] -]', '', $slugIt);
$slugIt = #iconv('UTF-8', 'ASCII//TRANSLIT', $slugIt);
[:alnum:] will match any alpha numeric character (including the ones with accent).
Take a look at http://php.net/manual/en/book.regex.php for more information on PHP's POSIX implementation.
In the end this turned out to be a combination of wrong character set in, AND how windows handles inconv.
First of all, i had an iso-8859 character set going in, and even though I was defining utf-8 in the head of the document, php was still treating the characterset as ISO.
Secondly, when using iconv in windows, you cannot apparently combine ASCII//TRANSLIT//IGNORE, which thankfully you can do in windows.
Now on linux, all accented characters are translated to their base character, and non-alpha numerics are removed.
Here's the new code
$slugIt = #iconv('iso-8859-1', 'ASCII//TRANSLIT//IGNORE', $slugIt);
$slugIt = preg_replace("/[^a-zA-Z0-9]/", "", $slugIt);