Regex to Remove All Special Characters from String

Regex remove all special characters except numbers?

Use the global flag:

var name = name.replace(/[^a-zA-Z ]/g, "");
                                    ^

If you don't want to remove numbers, add it to the class:

var name = name.replace(/[^a-zA-Z0-9 ]/g, "");

Regex to remove all special characters from string?

It really depends on your definition of special characters. I find that a whitelist rather than a blacklist is the best approach in most situations:

tmp = Regex.Replace(n, "[^0-9a-zA-Z]+", "");

You should be careful with your current approach because the following two items will be converted to the same string and will therefore be indistinguishable:

"TRA-12:123"
"TRA-121:23"

Remove all special characters except for @ symbol from string in JavaScript

If you want to keep the @ when it is followed by a word char and keeping the W is also ok and also remove the newlines, you could for example change the \s to match spaces or tabs [ \t]

Add the @ to the negated character class and use an alternation specifying to only match the @ when it is not followed by a word character using a negative lookahead.

[^\w \t@]+|@(?!\w)

• [^\w \t@]+ Match 1+ times any char except a word char, space or tab
• | Or
• @(?!\w) Match an @ not directly followed by a word char

Regex demo

In the replacement use an empty string.

How to remove all special characters except for underscore between two words in java?

The RegEx pattern, [^\p{Alnum}_]|^_|_$ meets your requirement.

import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        Stream.of(
                    "OIL~", 
                    "_OIL_GAS",
                    "OIL_GAS_", 
                    "_OIL_GAS_",
                    "*OIL_GAS$", 
                    "OIL_GAS"
                ).forEach(s -> System.out.println(s.replaceAll("[^\\p{Alnum}_]|^_|_$", "")));
    }
}

Output:

OIL
OIL_GAS
OIL_GAS
OIL_GAS
OIL_GAS
OIL_GAS

Explanation of the regex at regex101:

Note: As you must have already understood from the documentation, \p{Alnum} is same as A-Za-z0-9.

Python Regex - remove all "." and special characters EXCEPT the decimal point

Use a capturing group to capture only the decimal numbers and at the same time match special chars (ie. not of space and word characters).

Upon replacement, just refer to the capturing group in-order to make use of only the captured chars. ie. the whole match would be removed and replaced by the decimal number if exists.

s = 'What? The Census Says It’s Counted 99.9 Percent of Households. Don’t Be Fooled.'
import re
rgx = re.compile(r'(\d\.\d)|[^\s\w]')
rgx.sub(lambda x: x.group(1), s)
# 'What The Census Says Its Counted 99.9 Percent of Households Dont Be Fooled'

OR

Match all the dots except the one exists between the numbers and all chars except special chars and then finally replace those match chars with an empty string.

re.sub(r'(?!<\d)\.(?!\d)|[^\s\w.]', '', s)
# 'What The Census Says Its Counted 99.9 Percent of Households Dont Be Fooled'
 

Regex to remove all special characters except periods

You can use

"""[\p{P}\p{S}&&[^.]]+""".toRegex()

The [\p{P}\p{S}&&[^.]]+ pattern matches one or more (+) punctuation proper (\p{P}) or symbol (\p{S}) chars other than dots (&&[^.], using character class subtraction).

See a Kotlin demo:

println("a-b)h.".replace("""[\p{P}\p{S}&&[^.]]+""".toRegex(), ""))
// => abh.

How to remove all special Characters from a string except - . and space

Use either \s or simply a space character as explained in the Pattern class javadoc

\s - A whitespace character: [ \t\n\x0B\f\r]
   - Literal space character

You must either escape - character as \- so it won't be interpreted as range expression or make sure it stays as the last regex character. Putting it all together:

filename.replaceAll("[^a-zA-Z0-9\\s.-]", "")
filename.replaceAll("[^a-zA-Z0-9 .-]", "")

How to remove all special characters from a column name string using regular expressions

Try This:

DECLARE @str VARCHAR(400)='S$d#@gh'
DECLARE @expres  VARCHAR(50) = '%[~,@,#,$,%,&,*,(,),.,!]%'

WHILE PATINDEX( @expres, @str ) > 0
SET @str = Replace(REPLACE( @str, SUBSTRING( @str, PATINDEX( @expres, @str ), 1 ),''),'-',' ')
SELECT @str

You can Create a SCALAR FUNCTION & pass this Column

CREATE FUNCTION dbo.Remove_SpecialCharacters( @str VARCHAR(MAX))
RETURNS VARCHAR(MAX) AS
BEGIN
DECLARE @expres  VARCHAR(50) = '%[~,@,#,$,%,&,*,(,),.,!]%'

WHILE PATINDEX( @expres, @str ) > 0
SET @str = Replace(REPLACE( @str, SUBSTRING( @str, PATINDEX( @expres, @str ), 1 ),''),'-',' ')
RETURN @str
END

O/P

SELECT dbo.Remove_SpecialCharacters(COLUMNNAME),* FROM TABLENAME

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