My website and database is set to utf-8 and utf8mb4.
On textareas it's perfectly fine when users put utf-8 symbols/emojis.
But on certain input fields (name, address etc.) I want to remove the possibility of those "funny symbols", and only deal with basic text and numbers, including danish characters æøå, accents and symbols like -_'#()?=,.:;!"#&<> etc.
How would I go about this?
Is there some native php function to strip unicode symbols/characters, or do I have to find/make a specific regex function for it?
There are functions for checking encoding: http://php.net/manual/en/function.mb-check-encoding.php but to strip out characters I think you would need to use regex:
function StripNonUTF($str){
return preg_replace('/[^\pL\pM[:ascii:]]+/g', '', $str);
}
\pL matches any kind of letter from any language
\pM matches a character intended to be combined with another character (e.g. accents, umlauts, enclosing boxes, etc.)
[:ascii:] matches a character with ASCII value 0 through 127
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]/', '', $s);
I have a set of characters like
., !, ?, ;, (space)
and a string, which may or may not be UTF 8 (any language).
Is there a easy way to find out if the string has one of the character set above?
For example:
这是一个在中国的字符串。
which translates to
This is a string in chinese.
The dot character looks different in the first string. Is that a totally different character, or the dot correspondent in utf 8?
Or maybe there's a list somewhere with Unicode punctuation character codes?
In Unicode there are character propertiesPHP Docs, for example Symbols, Letters and the like. You can search for any string of a specific class with preg_matchDocs and the u modifier.
echo preg_match('/pP$/u', $str);
However, your string needs to be UTF-8 to do that.
You can test this on your own, I created a little script that tests for all properties via preg_match:
Looking for properties of last character in "Test.":
Found Punctuation (P).
Found Other punctuation (Po).
Looking for properties of last character in "这是一个在中国的字符串。":
Found Punctuation (P).
Found Other punctuation (Po).
Related: PHP - Fast way to strip all characters not displayable in browser from utf8 string.
Yes, 。 (U+3002, IDEOGRAPHIC FULL STOP) is a totally different character than . (U+002E, FULL STOP). If you want to find out whether a string contains one of the listed characters, you can use regular expressions:
preg_match('/[.!?;。]/u', $str, $match)
This will return either 0 or 1 and $match will contain the matched character. With this it’s important that your string in $str is properly encoded in UTF-8.
If you want to match any Unicode punctuation character, you can use the pattern \p{P} to describe the Unicode character property instead:
/\p{P}/u
you are not trying to transliterate, you are trying to translate!
UTF-8 is not a language, is a unicode character set that supports (virtually) all languages known in the world
what you are trying to do is something like this:
echo iconv("UTF-8", "ASCII//TRANSLIT//IGNORE", "这是一个在中国的字符串。");
echo iconv("UTF-8", "ASCII//TRANSLIT//IGNORE", "à è ò ù");
that not works with your chinese example
Is there a simple regex that will catch all non-english characters? It would need to allow common punctation and symbols, but no special characters such as Russian, Japanese, etc.
Looking for something to work in PHP.
Since in your comment your referring to addresses, they might contain digits too. So:
preg_replace('/[^[:alpha:][:punct:][:digit:]]/u', utf8_encode($input), '');
Should replace your unwanted characters. The [:alpha:] class will only work, if your locale is set up correctly, though. If, for example, it's set to de_DE, not only "a" through "z" are regarded characters, but also "exotics" like "ä", "ö", "è", and the like.
Also, since you don't want "Russian, Japanese, etc.", note the u modifier. The input has to be UTF-8 encoded in order to not break it and give you wrong results.
Such as this one [^A-Za-z0-9\,\.\-]?
This q/a seemed to handle it: PHP Validate string characters are UK or US Keyboard characters
use hex codes, e.g. this cleans out all non-ascii characters as well as line endings, and replaces them with spaces. space (\x20) is deliberately left out of the range so that consecutive runs of spaces and/or special chars are replaced with a single space.
$clean = trim(preg_replace('/[^\x21-\x7E]+/', ' ', $input));
if (strlen($str) == strlen(utf8_decode($str))) {
}
How can I remove control characters like STX from a PHP string? I played around with
preg_replace("/[^a-zA-Z0-9 .\-_;!:?äÄöÖüÜß<>='\"]/","",$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);