We Keep Coding

C# Char Array remove at specific index

Not to sure the best way to remove the char from the char array if the char at a given index is a number.
private string TextBox_CharacterCheck(string tocheckTextBox)
{
char[] charlist = tocheckTextBox.ToCharArray();
foreach (char character in charlist)
{
if (char.IsNumber(character))
{
}
}
return (new string(charlist));
}
Thanks in advance.
// this is now resolved. thank you to all who contributed

You could use the power of Linq:
return new string(tocheckTextBox.Where(c => !char.IsNumber(c)).ToArray())

This is fairly easy using Regex:
var result = Regex.Replace("a1b2c3d4", #"\d", "");
(as #Adassko notes, you can use "[0-9]" instead of #"\d" if you just want the digits 0 to 9, and not any other numeric characters).
You can also do it fairly efficiently using a StringBuilder:
var sb = new StringBuilder();
foreach (var ch in "a1b2c3d4")
{
if (!char.IsNumber(ch))
{
sb.Append(ch);
}
}
var result = sb.ToString();
You can also do it with linq:
var result = new string("a1b2c3d4".Where(x => !char.IsNumber(x)).ToArray());

Use Regex:
private string TextBox_CharacterCheck(string tocheckTextBox)
{
return Regex.Replace(tocheckTextBox, #"[\d]", string.Empty);;
}

System.String is immutable. You could use string.Replace or a regular expression to remove unwanted characters into a new string.

your best bet is to use regular expressions.
strings are immutable meaning that you can't change them - you need to rewrite the whole string - to do it in optimal way you should use StringBuilder class and Append every character that you want.
Also watch out for your code - char.IsNumber checks not only for characters 0-9, it also returns true for every numeric character such as ٢ and you probably don't want that.
here's the full list of characters returning true:
0123456789٠١٢٣٤٥٦٧٨٩۰۱۲۳۴۵۶۷۸۹߀߁߂߃߄߅߆߇߈߉०१२३४५६७८९০১২৩৪৫৬৭৮৯੦੧੨੩੪੫੬੭੮੯૦૧૨૩૪૫૬૭૮૯୦୧୨୩୪୫୬୭୮୯௦௧௨௩௪௫௬௭௮௯౦౧౨౩౪౫౬౭౮౯೦೧೨೩೪೫೬೭೮೯൦൧൨൩൪൫൬൭൮൯๐๑๒๓๔๕๖๗๘๙໐໑໒໓໔໕໖໗໘໙༠༡༢༣༤༥༦༧༨༩၀၁၂၃၄၅၆၇၈၉႐႑႒႓႔႕႖႗႘႙០១២៣៤៥៦៧៨៩᠐᠑᠒᠓᠔᠕᠖᠗᠘᠙᥆᥇᥈᥉᥊᥋᥌᥍᥎᥏᧐᧑᧒᧓᧔᧕᧖᧗᧘᧙᭐᭑᭒᭓᭔᭕᭖᭗᭘᭙᮰᮱᮲᮳᮴᮵᮶᮷᮸᮹᱀᱁᱂᱃᱄᱅᱆᱇᱈᱉᱐᱑᱒᱓᱔᱕᱖᱗᱘᱙꘠꘡꘢꘣꘤꘥꘦꘧꘨꘩꣐꣑꣒꣓꣔꣕꣖꣗꣘꣙꤀꤁꤂꤃꤄꤅꤆꤇꤈꤉꩐꩑꩒꩓꩔꩕꩖꩗꩘꩙０１２３４５６７８９
you should also use [0-9] rather than \d in your regular expressions if you want only parsable digits.
You can also use a trick to .Split your string on your character, then .Join it back. This not only allows you to remove one or more characters, it also lets you to replace it with some other character.
I use this trick to remove incorrect characters from file name:
string.Join("-", possiblyIncorrectFileName.Split(Path.GetInvalidFileNameChars()))
this code will replace any character that cannot be used in valid file name to -

You can use LINQ to remove the char from the char array if the char at a given index is a number.
CODE
//This will return you the list of char discarding the number.
var removedDigits = tocheckTextBox.Where(x => !char.IsDigit(x));
//This will return the string without numbers.
string output = string.join("", removedDigits);

how to deal with string.split by position

I'd like to ask one question about String.Split
For example:
char[] semicolon=new [] {';'};
char[] bracket=new [] {'[',']'};
string str="AND[Firstpart;Sndpart]";
I can split str by bracket and then split by semicolon.
Finally,I get the Firstpart and Sndpart in the bracket.
But If str="AND[AND[Firstpart;Sndpart];sndpart];
How can I get AND[Firpart;Sndpart] and sndpart?
Is there a way to tell c# to split by second semicolon?
Thanks for your help

One way is to hide characters inside bracket with a character that is not used in any of your strings.
Method HideSplit: This method will change separator characters inside brackets with fake ones. Then it will perform split and will give back the result with original characters.
This method maybe an overkill if you want to do this many times. but you should be able to optimize it easily if you got the idea.
private static void Main()
{
char[] semicolon = new[] { ';' };
char[] bracket = new[] { '[', ']' };
string str = "AND[AND[Firstpart;Sndpart];sndpart]";
string[] splitbyBracket = HideSplit(str, bracket);
}
private static string[] HideSplit(string str,char[] separator)
{
int counter = 0; // When counter is more than 0 it means we are inside brackets
StringBuilder result = new StringBuilder(); // To build up string as result
foreach (char ch in str)
{
if(ch == ']') counter--;
if (counter > 0) // if we are inside brackets perform hide
{
if (ch == '[') result.Append('\uFFF0'); // add '\uFFF0' instead of '['
else if (ch == ']') result.Append('\uFFF1');
else if (ch == ';') result.Append('\uFFF2');
else result.Append(ch);
}
else result.Append(ch);
if (ch == '[') counter++;
}
string[] split = result.ToString().Split(separator); // Perform split. (characters are hidden now)
return split.Select(x => x
.Replace('\uFFF0', '[')
.Replace('\uFFF1', ']')
.Replace('\uFFF2', ';')).ToArray(); // unhide characters and give back result.
// dont forget: using System.Linq;
}
Some examples :
string[] a1 = HideSplit("AND[AND[Firstpart;Sndpart];sndpart]", bracket);
// Will give you this array { AND , AND[Firstpart;Sndpart];sndpart }
string[] a2 = HideSplit("AND[Firstpart;Sndpart];sndpart", semicolon);
// Will give you this array { AND[Firstpart;Sndpart] , sndpart }
string[] a3 = HideSplit("AND[Firstpart;Sndpart]", bracket);
// Will give you this array { AND , Firstpart;Sndpart }
string[] a4 = HideSplit("Firstpart;Sndpart", semicolon);
// Will give you this array { Firstpart , Sndpart }
And you can continue splitting this way.

Is there a way to tell c# to split by second semicolon?
There is no direct way to do that, but if that is precisely what you want, it's not hard to achieve:
string str="AND[AND[Firstpart;Sndpart];sndpart];
string[] tSplits = str.Split(';', 3);
string[] splits = { tSplits[0] + ";" + tSplits[1], tSplits[2] };
You could achieve the same result using a combination of IndexOf() and Substring(), however that is most likely not what you'll end up using as it's too specific and not very helpful for various inputs.
For your case, you need something that understands context.
In real-world complex cases you'd probably use a lexer / parser, but that seems like an overkill here.
Your best effort would probably be to use a loop, walk through all characters while counting +/- square brackets and spliting when you find a semicolon & the count is 1.

You can use Regex.Split, which is a more flexible form of String.Split:
string str = "AND[AND[Firstpart;Sndpart];sndpart]";
string[] arr = Regex.Split(str, #"(.*?;.*?;)");
foreach (var s in arr)
Console.WriteLine("'{0}'", s);
// output: ''
// 'AND[AND[Firstpart;Sndpart];'
// 'sndpart]'
Regex.Split splits not by chars, but by a string matching a regex expression, so it comes down to constructing a regex pattern meeting particular requirements. Splitting by a second semicolon is in practice splitting by a string that ends in a semicolon and that contains another semicolon before, so the matching pattern by which you split the input string could be for example: (.*?;.*?;).
The returned array has three elements instead of two because the splitting regex matches the beginning of the input string, in this case the empty string is returned as the first element.
You can read more on Regex.Split on msdn.

Fastest way to remove the leading special characters in string in c#

I am using c# and i have a string like
-Xyz
--Xyz
---Xyz
-Xyz-Abc
--Xyz-Abc
i simply want to remove any leading special character until alphabet comes , Note: Special characters in the middle of string will remain same . What is the fastest way to do this?

You could use string.TrimStart and pass in the characters you want to remove:
var result = yourString.TrimStart('-', '_');
However, this is only a good idea if the number of special characters you want to remove is well-known and small.
If that's not the case, you can use regular expressions:
var result = Regex.Replace(yourString, "^[^A-Za-z0-9]*", "");

I prefer this two methods:
List<string> strings = new List<string>()
{
"-Xyz",
"--Xyz",
"---Xyz",
"-Xyz-Abc",
"--Xyz-Abc"
};
foreach (var s in strings)
{
string temp;
// String.Trim Method
char[] charsToTrim = { '*', ' ', '\'', '-', '_' }; // Add more
temp = s.TrimStart(charsToTrim);
Console.WriteLine(temp);
// Enumerable.SkipWhile Method
// Char.IsPunctuation Method (se also Char.IsLetter, Char.IsLetterOrDigit, etc.)
temp = new String(s.SkipWhile(x => Char.IsPunctuation(x)).ToArray());
Console.WriteLine(temp);
}

Is there a method for removing whitespace characters from a string?

Is there a string class member function (or something else) for removing all spaces from a string? Something like Python's str.strip() ?

You could simply do:
myString = myString.Replace(" ", "");
If you want to remove all white space characters you could use Linq, even if the syntax is not very appealing for this use case:
myString = new string(myString.Where(c => !char.IsWhiteSpace(c)).ToArray());

String.Trim method removes trailing and leading white spaces. It is the functional equivalent of Python's strip method.

LINQ feels like overkill here, converting a string to a list, filtering the list, then turning it back onto a string. For removal of all white space, I would go for a regular expression. Regex.Replace(s, #"\s", ""). This is a common idiom and has probably been optimized.

If you want to remove the spaces that prepend the string or at itt's end, you might want to have a look at TrimStart() and TrimEnd() and Trim().

If you're looking to replace all whitespace in a string (not just leading and trailing whitespace) based on .NET's determination of what's whitespace or not, you could use a pretty simple LINQ query to make it work.
string whitespaceStripped = new string((from char c in someString
where !char.IsWhiteSpace(c)
select c).ToArray());

Yes, Trim.
String a = "blabla ";
var b = a.Trim(); // or TrimEnd or TrimStart

Yes, String.Trim().
var result = " a b ".Trim();
gives "a b" in result. By default all whitespace is trimmed. If you want to remove only space you need to type
var result = " a b ".Trim(' ');
If you want to remove all spaces in a string you can use string.Replace().
var result = " a b ".Replace(" ", "");
gives "ab" in result. But that is not equivalent to str.strip() in Python.

I don't know much about Python...
IF the str.strip() just removes whitespace at the start and the end then you could use str = str.Trim() in .NET... otherwise you could just str = str.Replace ( " ", "") for removing all spaces.
IF it removes all whitespace then use
str = (from c in str where !char.IsWhiteSpace(c) select c).ToString()

There are many diffrent ways, some faster then others:
public static string StripTabsAndNewlines(this string s) {
//string builder (fast)
StringBuilder sb = new StringBuilder();
for (int i = 0; i < str.Length; i++) {
if ( ! Char.IsWhiteSpace(s[i])) {
sb.Append();
}
}
return sb.tostring();
//linq (faster ?)
return new string(input.ToCharArray().Where(c => !Char.IsWhiteSpace(c)).ToArray());
//regex (slow)
return Regex.Replace(s, #"\s+", "")
}

you could use
StringVariable.Replace(" ","")

I'm surprised no one mentioned this:
String.Join("", " all manner\tof\ndifferent\twhite spaces!\n".Split())
string.Split by default splits along the characters that are char.IsWhiteSpace so this is a very similar solution to filtering those characters out by the direct use of char.IsWhiteSpace and it's a one-liner that works in pre-LINQ environments as well.

Strip spaces? Strip whitespaces? Why should it matter? It only matters if we're searching for an existing implementation, but let's not forget how fun it is to program the solution rather than search MSDN (boring).
You should be able to strip any chars from any string by using 1 of the 2 functions below.
You can remove any chars like this
static string RemoveCharsFromString(string textChars, string removeChars)
{
string tempResult = "";
foreach (char c in textChars)
{
if (!removeChars.Contains(c))
{
tempResult = tempResult + c;
}
}
return tempResult;
}
or you can enforce a character set (so to speak) like this
static string EnforceCharLimitation(string textChars, string allowChars)
{
string tempResult = "";
foreach (char c in textChars)
{
if (allowChars.Contains(c))
{
tempResult = tempResult + c;
}
}
return tempResult;
}

Read text file word-by-word using LINQ

I am learning LINQ, and I want to read a text file (let's say an e-book) word by word using LINQ.
This is wht I could come up with:
static void Main()
{
string[] content = File.ReadAllLines("text.txt");
var query = (from c in content
select content);
foreach (var line in content)
{
Console.Write(line+"\n");
}
}
This reads the file line by line. If i change ReadAllLines to ReadAllText, the file is read letter by letter.
Any ideas?

string[] content = File.ReadAllLines("text.txt");
var words=content.SelectMany(line=>line.Split(' ', StringSplitOptions.RemoveEmptyEntries));
foreach(string word in words)
{
}
You'll need to add whatever whitespace characters you need. Using StringSplitOptions to deal with consecutive whitespaces is cleaner than the Where clause I originally used.
In .net 4 you can use File.ReadLines for lazy evaluation and thus lower RAM usage when working on large files.

string str = File.ReadAllText();
char[] separators = { '\n', ',', '.', ' ', '"', ' ' }; // add your own
var words = str.Split(separators, StringSplitOptions.RemoveEmptyEntries);

string content = File.ReadAllText("Text.txt");
var words = from word in content.Split(WhiteSpace, StringSplitOptions.RemoveEmptyEntries)
select word;
You will need to define the array of whitespace chars with your own values like so:
List<char> WhiteSpace = { Environment.NewLine, ' ' , '\t'};
This code assumes that panctuation is a part of the word (like a comma).

It's probably better to read all the text using ReadAllText() then use regular expressions to get the words. Using the space character as a delimiter can cause some troubles as it will also retrieve punctuation (commas, dots .. etc). For example:
Regex re = new Regex("[a-zA-Z0-9_-]+", RegexOptions.Compiled); // You'll need to change the RE to fit your needs
Match m = re.Match(text);
while (m.Success)
{
string word = m.Groups[1].Value;
// do your processing here
m = m.NextMatch();
}

The following uses iterator blocks, and therefore uses deferred loading. Other solutions have you loading the entire file into memory before being able to iterate over the words.
static IEnumerable<string> GetWords(string path){
foreach (var line in File.ReadLines(path)){
foreach (var word in line.Split(null)){
yield return word;
}
}
}
(Split(null) automatically removes whitespace)
Use it like this:
foreach (var word in GetWords(#"text.txt")){
Console.WriteLine(word);
}
Works with standard Linq funness too:
GetWords(#"text.txt").Take(25);
GetWords(#"text.txt").Where(w => w.Length > 3)
Of course error handling etc. left out for sake of learning.

You could write content.ToList().ForEach(p => p.Split(' ').ToList().ForEach(Console.WriteLine)) but that's not a lot of linq.