I wanted to know how to represent a whitespace character in C#. I found the empty string representation string.Empty. Is there anything like that that represents a whitespace character?
I would like to do something like this:
test.ToLower().Split(string.Whitespace)
//test.ToLower().Split(Char.Whitespace)
Which whitespace character? The empty string is pretty unambiguous - it's a sequence of 0 characters. However, " ", "\t" and "\n" are all strings containing a single character which is characterized as whitespace.
If you just mean a space, use a space. If you mean some other whitespace character, there may well be a custom escape sequence for it (e.g. "\t" for tab) or you can use a Unicode escape sequence ("\uxxxx"). I would discourage you from including non-ASCII characters in your source code, particularly whitespace ones.
EDIT: Now that you've explained what you want to do (which should have been in your question to start with) you'd be better off using Regex.Split with a regular expression of \s which represents whitespace:
Regex regex = new Regex(#"\s");
string[] bits = regex.Split(text.ToLower());
See the Regex Character Classes documentation for more information on other character classes.
No, there isn't such constant.
The WhiteSpace CHAR can be referenced using ASCII Codes here.
And Character# 32 represents a white space, Therefore:
char space = (char)32;
For example, you can use this approach to produce desired number of white spaces anywhere you want:
int _length = {desired number of white spaces}
string.Empty.PadRight(_length, (char)32));
So I had the same problem so what I did was create a string with a white space and just index the character.
String string = "Hello Morning Good Night";
char empty = string.charAt(5);
Now whenever I need a empty character I will pull it from my reference in memory.
Which whitespace character? The most common is the normal space, which is between each word in my sentences. This is just " ".
Using regular expressions, you can represent any whitespace character with the metacharacter "\s"
MSDN Reference
You can always use Unicode character, for me personally this is the most clear solution:
var space = "\u0020"
Related
i would appreciate your help on this, since i do not know which range of characters to use, or if there is a character class like [[:cntrl:]] that i have found in ruby?
by means of non printable, i mean delete all characters that are not shown in ie output, when one prints the input string. Please note, i look for a c# regex, i do not have a problem with my code
You may remove all control and other non-printable characters with
s = Regex.Replace(s, #"\p{C}+", string.Empty);
The \p{C} Unicode category class matches all control characters, even those outside the ASCII table because in .NET, Unicode category classes are Unicode-aware by default.
Breaking it down into subcategories
To only match basic control characters you may use \p{Cc}+, see 65 chars in the Other, Control Unicode category. It is equal to a [\u0000-\u0008\u000E-\u001F\u007F-\u0084\u0086-\u009F \u0009-\u000D \u0085]+ regex.
To only match 161 other format chars including the well-known soft hyphen (\u00AD), zero-width space (\u200B), zero-width non-joiner (\u200C), zero-width joiner (\u200D), left-to-right mark (\u200E) and right-to-left mark (\u200F) use \p{Cf}+. The equivalent including astral place code points is a (?:[\xAD\u0600-\u0605\u061C\u06DD\u070F\u08E2\u180E\u200B-\u200F\u202A-\u202E\u2060-\u2064\u2066-\u206F\uFEFF\uFFF9-\uFFFB]|\uD804[\uDCBD\uDCCD]|\uD80D[\uDC30-\uDC38]|\uD82F[\uDCA0-\uDCA3]|\uD834[\uDD73-\uDD7A]|\uDB40[\uDC01\uDC20-\uDC7F])+ regex.
To match 137,468 Other, Private Use control code points you may use \p{Co}+, or its equivalent including astral place code points, (?:[\uE000-\uF8FF]|[\uDB80-\uDBBE\uDBC0-\uDBFE][\uDC00-\uDFFF]|[\uDBBF\uDBFF][\uDC00-\uDFFD])+.
To match 2,048 Other, Surrogate code points that include some emojis, you may use \p{Cs}+, or [\uD800-\uDFFF]+ regex.
You can try with :
string s = "Täkörgåsmrgås";
s = Regex.Replace(s, #"[^\u0000-\u007F]+", string.Empty);
Updated answer after comments:
Documentation about non-printable character:
https://en.wikipedia.org/wiki/Control_character
Char.IsControl Method:
https://msdn.microsoft.com/en-us/library/system.char.iscontrol.aspx
Maybe you can try:
string input; // this is your input string
string output = new string(input.Where(c => !char.IsControl(c)).ToArray());
To remove all control and other non-printable characters
Regex.Replace(s, #"\p{C}+", String.Empty);
To remove the control characters only (if you don't want to remove the emojis 😎)
Regex.Replace(s, #"\p{Cc}+", String.Empty);
you can try this:
public static string TrimNonAscii(this string value)
{
string pattern = "[^ -~]*";
Regex reg_exp = new Regex(pattern);
return reg_exp.Replace(value, "");
}
So, let's suppose I have an array of special characters, for example, ".[]{}()\/*+?|^$"
What I want to do is take an input string, for example, ".com", and replace all occurences of special characters with the same character but with a "\" preppended to it.
So for example, the result for that input would be "\.com"
My approach was to iterate over the array of special characters, and search in the input string for the occurence of the current special character, and do the replacement.
The problem is that a "." would be found and replaced with "\.", but then "\" is a special character itself, so it would later be found and be replaced to "\\.".
How can I avoid this and still keep "\" as an special character?
(I want "\" to be replaced with "\\", but not in these situations).
I hope I made myself clear enough.
Thank you all for your reading!
Looking at these special characters ".[]{}()\/*+?|^$" as they are regex charactes, I believe you are looking for Regex.Escape method.
If I understand your question, the simple solution seems to be just having '\' be the first element in your array of special characters - then, you replace the '\' characters in the string with '\', '.' with '.' etc, but you don't re-replace the generated '\'s.
I use the following regex, which is working, but I want to add a condition so as to accept spaces at the end of the value. Currently it is not working.
What am I missinghere?
^[a-zA-Z][a-zA-Z0-9_]+\s?$[\s]*$
Assumption: you added the two end of string anchors $ by mistake.
? quantifier, matching one or zero repetitions, makes the previous item optional
* quantifier, matching zero or more repetitions
So change your expression to
^[a-zA-Z][a-zA-Z0-9_]+\s*$
this is matching any amount of whitespace at the end of the string.
Be aware, whitespace is not just the space character, it is also tabs and newlines (and more)!
If you really want to match only space, just write a space or make a character class with all the characters you want to match.
^[a-zA-Z][a-zA-Z0-9_]+ *$
or
^[a-zA-Z][a-zA-Z0-9_]+[ \t]*$
Next thing is: Are you sure you only want plain ASCII letters? Today there is Unicode and you can use Unicode properties, scripts and blocks in your regular expressions.
Your expression in Unicode, allowing all letters and digits.
^\p{L}\w+\s*$
\p{L} Unicode property, any kind of letter from any language.
\w shorthand character class for word characters (letters, digits and connector characters like "_") [\p{L}\p{Nd}\p{Pc}] as character class with Unicode properties. Definition on msdn
why two dollars?
^[a-zA-Z][a-zA-Z0-9_]+\s*$
or make it this :
"^[a-zA-Z][a-zA-Z0-9_]+\s?\$\s*$"
if you want to literally match the dollar.
Try this -
"^[a-zA-Z][a-zA-Z0-9_]+(\s)?$"
or this -
"^[a-zA-Z][a-zA-Z0-9_]+((\s){,})$"
$ indicates end of expression, if you are looking $ as character, then escape it with \
My Regex is removing all numeric (0-9) in my string.
I don't get why all numbers are replaced by _
EDIT: I understand that my "_" regex pattern changes the characters into underscores. But not why numbers!
Can anyone help me out? I only need to remove like all special characters.
See regex here:
string symbolPattern = "[!##$%^&*()-=+`~{}'|]";
Regex.Replace("input here 12341234" , symbolPattern, "_");
Output: "input here ________"
The problem is your pattern uses a dash in the middle, which acts as a range of the ascii characters from ) to =. Here's a breakdown:
): 41
1: 49
=: 61
As you can see, numbers start at 49, and falls between the range of 41-61, so they're matched and replaced.
You need to place the - at either the beginning or end of the character class for it to be matched literally rather than act as a range:
"[-!##$%^&*()=+`~{}'|]"
you must escape - because sequence [)-=] contains digits
string symbolPattern = "[!##$%^&*()\-=+`~{}'|]";
Move the - to the end of the list so it is seen as a literal:
"[!##$%^&*()=+`~{}'|-]"
Or, to the front:
"[-!##$%^&*()=+`~{}'|]"
As it stands, it will match all characters in the range )-=, which includes all numerals.
You need to escape your special characters in your regex. For instance, * is a wildcard match. Look at what some of those special characters mean for your match.
I've not used C#, but typically the "*" character is also a control character that would need escaping.
The following matches a whole line of any characters, although the "^" and "$" are some what redundant:
^.*$
This matches any number of "A" characters that appear in a string:
A*
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I have a parsing question. I have a paragraph which has instances of : word . So basically it has a colon, two spaces, a word (could be anything), then two more spaces.
So when I have those instances I want to convert the string so I have
A new line character after : and the word.
Removed the double space after the word.
Replace all double spaces with new line characters.
Don't know exactly how about to do this. I'm using C# to do this. Bullet point 2 above is what I'm having a hard time doing this.
Thanks
Assuming your original string is exactly in the form you described, this will do:
var newString = myString.Trim().Replace(" ", "\n");
The Trim() removes leading and trailing whitespaces, taking care of your spaces at the end of the string.
Then, the Replace replaces the remaining " " two space characters, with a "\n" new line character.
The result is assigned to the newString variable. This is needed, as myString will not change - as strings in .NET are immutable.
I suggest you read up on the String class and all its methods and properties.
You can try
var str = ": first : second ";
var result = Regex.Replace(str, ":\\s{2}(?<word>[a-zA-Z0-9]+)\\s{2}",
":\n${word}\n");
Using RegularExpressions will give you exact matches on what you are looking for.
The regex match for a colon, two spaces, a word, then two more spaces is:
Dim reg as New Regex(": [a-zA-Z]* ")
[a-zA-Z] will look for any character within the alphabetical range. Can append 0-9 on as well if you accept numbers within the word. The * afterwards indicated that there can be 0 or more instances of the preceding value.
[a-zA-Z]* will attempt to do a full match of any set of contiguous alpha characters.
Upon further reading, you may use [\w] in place of [a-zA-Z0-9] if that's what you are looking for. This will match any 'word' character.
source: http://msdn.microsoft.com/en-us/library/ms972966.aspx
You can retrieve all the matches using reg.Matches(inputString).
Review http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex.replace.aspx for more information on regular expression replacements and your options from there out
edit: Before I was using \s to search for spaces. This will match any whitespace character including tabs, new lines and other. That is not what we want, so I reverted it back to search for exact space characters.
You can use string.TrimEnd - http://msdn.microsoft.com/en-us/library/system.string.trimend.aspx - to trim spaces at the end of the string.
The following is an example using Regular Expressions. See also this question for more info.
Basically the pattern string tells the regex to look for a colon followed by two spaces. Then we save in a capture group named "word" whatever the word is surrounded by two spaces on either side. Finally two more spaces are specified to finish the pattern.
The replace uses a lambda which says for every match, replace it with a colon, a new line, the "lone" word, and another newline.
string Paragraph = "Jackdaws love my big sphinx of quartz: fizz The quick onyx goblin jumps over the lazy dwarf. Where: buzz The crazy dogs.";
string Pattern = #": (?<word>\S*) ";
string Result = Regex.Replace(Paragraph, Pattern, m =>
{
var LoneWord = m.Groups[1].Value;
return #":" + Environment.NewLine + LoneWord + Environment.NewLine;
},
RegexOptions.IgnoreCase);
Input
Jackdaws love my big sphinx of quartz: fizz The quick onyx goblin jumps over the lazy dwarf. Where: buzz The crazy dogs.
Output
Jackdaws love my big sphinx of quartz:
fizz
The quick onyx goblin jumps over the lazy dwarf. Where:
buzz
The quick brown fox.
Note, for item 3 on your list, if you also want to replace individual occurrences of two spaces with newlines, you could do this:
Result = Result.Replace(" ", Environment.NewLine);