I'm trying to catch any characters that are not letters, numbers, or .-_ (period, dash, underscore)
My code is
return !preg_match('/[^A-Za-z0-9.-_]/', $strToFilter);
My hope is that it will return false when it find an invalid character. As of now it allows ._ (period and underscore) but does not allow - (dash). It also does not detect characters like /, \, [, ], %, ^, etc as invalid characters.
What is wrong with my expression?
In Regex character classes, you can't match a literal hyphen unless it is:
immediately against either bracket,
follows the negate caret (^), or
is escaped using the backslash (\)
The hyphen can be included right after the opening bracket, or right before the closing bracket, or right after the negating caret. Both [-x] and [x-] match an x or a hyphen. [^-x] and [^x-] match any character thas is not an x or a hyphen. This works in all flavors discussed in this tutorial. Hyphens at other positions in character classes where they can't form a range may be interpreted as literals or as errors. Regex flavors are quite inconsistent about this.
Source - See Metacharacters Inside Character Classes.
Just escape the dash:
return !preg_match('/[^A-Za-z0-9.\-_]/', $strToFilter);
I've made this regex:
^[a-zA-Z0-9_.-]*$
Supports:
letters [uppercase and lowercase]
numbers [from 0 to 9]
underscores [_]
dots [.]
hyphens [-]
Now, I want to add these:
spaces [ ]
comma [,]
exclamation mark [!]
parenthesis [()]
plus [+]
equal [=]
apostrophe [']
double quotation mark ["]
at [#]
dollar [$]
percent [%]
asterisk [*]
For example, this code accept only some of the symbols above:
^[a-zA-Z0-9 _.,-!()+=“”„#"$#%*]*$
Returns:
Warning: preg_match(): Compilation failed: range out of order in character class at offset 16
Make sure to put hyphen - either at start or at end in character class otherwise it needs to be escaped. Try this regex:
^[a-zA-Z0-9 _.,!()+=`,"#$#%*-]*$
Also note that because * it will even match an empty string. If you don't want to match empty strings then use +:
^[a-zA-Z0-9 _.,!()+=`,"#$#%*-]+$
Or better:
^[\w .,!()+=`,"#$#%*-]+$
TEST:
$text = "_.,!()+=,#$#%*-";
if(!preg_match('/\A[\w .,!()+=`,"#$#%*-]+\z/', $text)) {
echo "error.";
}
else {
echo "OK.";
}
Prints:
OK.
The hyphen is being treated as a range marker -- when it sees ,-! it thinks you're asking for a range all characters in the charset that fall between , and ! (ie the same way that A-Z works. This isn't what you want.
Either make sure the hyphen is the last character in the character class, as it was before, or escape it with a backslash.
I would also point out that the quote characters you're using “”„ are part of an extended charset, and are not the same as the basic ASCII quotes "'. You may want to include both sets in your pattern. If you do need to include the non-ASCII characters in the pattern, you should also add the u modifier after the end of your pattern so it correctly picks up unicode characters.
Try escaping your regex: [a-zA-Z0-9\-\(\)\*]
Check if this help you: How to escape regular expression special characters using javascript?
Inside of a character class [...] the hyphen - has a special meaning unless it is the first or last character, so you need to escape it:
^[a-zA-Z0-9 _.,\-!()+=“”„#"$#%*]*$
None of the other characters need to be escaped in the character class (except ]). You will also need to escape the quote indicating the string. e.g.
'/[\']/'
"/[\"]/"
try this
^[A-Z0-9][A-Z0-9*&!_^%$#!~#,=+,./\|}{)(~`?][;:\'""-]{0,8}$
use this link to test
trick is i reverse ordered the parenthesis and other braces that took care of some problems. And for square braces you must escape them
So I want to validate a string based on whether or not it contains only grammatical characters as well as numbers and letters.(basically A-Z, a-z, 0-9, plus periods(.), commas(,) colons(:), semicolons(;), hyphens(-), single quotes('), double quotes(") and parentheses(). I am getting a PHP error that says "Compilation failed: range out of order in character clas". What regex code should I be using?
This is the one I'm currently using:
^[a-zA-Z0-9_:;-()'\" ]*^
You need to escape - which would then become this ^[a-zA-Z0-9_:;\-()'\" ]* . - has a special meaning inside character set so it needs to be escaped. ^ in the end is also not necessary. The regex can also simplified using \w like this
^[\w:;()'"\s-]*
\w matches letters, digits, and underscores.
The problem is that you have a dash character in the regex, which the parser is interpreting as a range instead of as a literal dash. You can fix that by:
Escaping it with a backslash (^[a-zA-Z0-9_:;\-()'\" ]*^)
Putting it at the start (^[-a-zA-Z0-9_:;()'\" ]*^)
Putting it at the end (^[a-zA-Z0-9_:;()'\" -]*^)
I'm still kinda new to using Regular Expressions, so here's my plight. I have some rules for acceptable usernames and I'm trying to make an expression for them.
Here they are:
1-15 Characters
a-z, A-Z, 0-9, and spaces are acceptable
Must begin with a-z or A-Z
Cannot end in a space
Cannot contain two spaces in a row
This is as far as I've gotten with it.
/^[a-zA-Z]{1}([a-zA-Z0-9]|\s(?!\s)){0,14}[^\s]$/
It works, for the most part, but doesn't match a single character such as "a".
Can anyone help me out here? I'm using PCRE in PHP if that makes any difference.
Try this:
/^(?=.{1,15}$)[a-zA-Z][a-zA-Z0-9]*(?: [a-zA-Z0-9]+)*$/
The look-ahead assertion (?=.{1,15}$) checks the length and the rest checks the structure:
[a-zA-Z] ensures that the first character is an alphabetic character;
[a-zA-Z0-9]* allows any number of following alphanumeric characters;
(?: [a-zA-Z0-9]+)* allows any number of sequences of a single space (not \s that allows any whitespace character) that must be followed by at least one alphanumeric character (see PCRE subpatterns for the syntax of (?:…)).
You could also remove the look-ahead assertion and check the length with strlen.
make everything after your first character optional
^[a-zA-Z]?([a-zA-Z0-9]|\s(?!\s)){0,14}[^\s]$
The main problem of your regexp is that it needs at least two characters two have a match :
one for the [a-zA-Z]{1} part
one for the [^\s] part
Beside this problem, I see some parts of your regexp that could be improved :
The [^\s] class will match any character, except spaces : a dot or semi-colon will be accepted, try to use the [a-zA-Z0-9] class here to ensure the character is a correct one.
You can delete the {1} part at the beginning, as the regexp will match exactly one character by default
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);