what is the faster way to trim all alphabet in a string that have alphabet prefix.
For example, input sting "ABC12345" , and i wish to havee 12345 as output only.
Thanks.
Please use "char.IsDigit", try this:
static void Main(string[] args)
{
var input = "ABC12345";
var numeric = new String(input.Where(char.IsDigit).ToArray());
Console.Read();
}
You can use Regular Expressions to trim an alphabetic prefix
var input = "ABC123";
var trimmed = Regex.Replace(input, #"^[A-Za-z]+", "");
// trimmed = "123"
The regular expression (second parameter) ^[A-Za-z]+ of the replace method does most of the work, it defines what you want to be replaced using the following rules:
The ^ character ensures a match only exists at the start of a string
The [A-Za-z] will match any uppercase or lowercase letters
The + means the upper or lowercase letters will be matched as many times in a row as possible
As this is the Replace method, the third parameter then replaces any matches with an empty string.
The other answers seem to answer what is the slowest way .. so if you really need the fastest way, then you can find the index of the first digit and get the substring:
string input = "ABC12345";
int i = 0;
while ( input[i] < '0' || input[i] > '9' ) i++;
string output = input.Substring(i);
The shortest way to get the value would probably be the VB Val method:
double value = Microsoft.VisualBasic.Conversion.Val("ABC12345"); // 12345.0
You would have to regular expression. It seems you are looking for only digits and not letters.
Sample:
string result =
System.Text.RegularExpressions.Regex.Replace("Your input string", #"\D+", string.Empty);
Related
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);
string temp = "12345&refere?X=Assess9677125?Folder_id=35478";
I need to extract the number 12345 alone and I don't need the numbers 9677125 and 35478.
What regex can I use?
Here is the regex for extracting 5 digit number in the beginning of the string:
^(\d{5})&
If length is arbitrary:
^(\d+)&
If termination pattern is not always &:
^(\d+)[^\d]
Based on the Sayse's comment you can simply rewrite as:
^(\d+)
and in case of the termination is some number(for instance 999) then:
^(\d+)999
You don't need regex if you only want to extract the first number:
string temp = "12345&refere?X=Assess9677125?Folder_id=35478";
int first = Int32.Parse(String.Join("", temp.TakeWhile(c => Char.IsDigit(c))));
Console.WriteLine(first); // 12345
If the number you want is always at the beginning of the string and terminated by an ampersand (&) you don't need a regex at all. Just split the string on the ampersand and get the first element of the resulting array:
String temp = "12345&refere?X=Assess9677125?Folder_id=35478";
var splitArray = String.Split('&', temp);
var number = splitArray[0]; // returns 12345
Alternatively, you can get the index of the ampersand and substring up to that point:
String temp = "12345&refere?X=Assess9677125?Folder_id=35478";
var ampersandIndex = temp.IndexOf("&");
var number = temp.SubString(0, ampersandIndex); // returns 12345
From what you haven given us this is fairly simple:
var regex = new Regex(#"^(?<number>\d+)&");
var match = regex.Match("12345&refere?X=Assess9677125?Folder_id=35478");
if (match.Success)
{
var number = int.Parse(match.Groups["number"].Value);
}
Edit: Of course you can replace the argument of new Regex with any of the combinations Giorgi has given.
I'm looking for a way to search a string for everything before a set of characters in C#. For Example, if this is my string value:
This is is a test.... 12345
I want build a new string with all of the characters before "12345".
So my new string would equal "This is is a test.... "
Is there a way to do this?
I've found Regex examples where you can focus on one character but not a sequence of characters.
You don't need to use a Regex:
public string GetBitBefore(string text, string end)
{
var index = text.IndexOf(end);
if (index == -1) return text;
return text.Substring(0, index);
}
You can use a lazy quantifier to match anything, followed by a lookahead:
var match = Regex.Match("This is is a test.... 12345", #".*?(?=\d{5})");
where:
.*? lazily matches everything (up to the lookahead)
(?=…) is a positive lookahead: the pattern must be matched, but is not included in the result
\d{5} matches exactly five digits. I'm assuming this is your lookahead; you can replace it
You can do so with help of regex lookahead.
.*(?=12345)
Example:
var data = "This is is a test.... 12345";
var rxStr = ".*(?=12345)";
var rx = new System.Text.RegularExpressions.Regex (rxStr,
System.Text.RegularExpressions.RegexOptions.IgnoreCase);
var match = rx.Match(data);
if (match.Success) {
Console.WriteLine (match.Value);
}
Above code snippet will print every thing upto 12345:
This is is a test....
For more detail about see regex positive lookahead
This should get you started:
var reg = new Regex("^(.+)12345$");
var match = reg.Match("This is is a test.... 12345");
var group = match.Groups[1]; // This is is a test....
Of course you'd want to do some additional validation, but this is the basic idea.
^ means start of string
$ means end of string
The asterisk tells the engine to attempt to match the preceding token zero or more times. The plus tells the engine to attempt to match the preceding token once or more
{min,max} indicate the minimum/maximum number of matches.
\d matches a single character that is a digit, \w matches a "word character" (alphanumeric characters plus underscore), and \s matches a whitespace character (includes tabs and line breaks).
[^a] means not so exclude a
The dot matches a single character, except line break characters
In your case there many way to accomplish the task.
Eg excluding digit: ^[^\d]*
If you know the set of characters and they are not only digit, don't use regex but IndexOf(). If you know the separator between first and second part as "..." you can use Split()
Take a look at this snippet:
class Program
{
static void Main(string[] args)
{
string input = "This is is a test.... 12345";
// Here we call Regex.Match.
MatchCollection matches = Regex.Matches(input, #"(?<MySentence>(\w+\s*)*)(?<MyNumberPart>\d*)");
foreach (Match item in matches)
{
Console.WriteLine(item.Groups["MySentence"]);
Console.WriteLine("******");
Console.WriteLine(item.Groups["MyNumberPart"]);
}
Console.ReadKey();
}
}
You could just split, not as optimal as the indexOf solution
string value = "oiasjdoiasj12345";
string end = "12345";
string result = value.Split(new string[] { end }, StringSplitOptions.None)[0] //Take first part of the result, not the quickest but fairly simple
Regex rgx2 = new Regex("[^[0-9] . \n\r\t]");
string dash = Regex.Replace(Des_AccNo.ToString(), #" ^-");
I need to clean this string 100-0#/2^2341?! as 100022341
I don't know what is your code, but you can do that by:
val = val.Replace("-", string.Empty)
If you want to remove all non-numeric characters:
string result = Regex.Replace(inputString, #"[^0-9]", "");
Basically what that says is "if the character isn't a digit, then replace it with the empty string." The ^ as the first character in the character group negates it. That is, [0-9] matches any digit. [^0-9] matches everything except a digit. See Character Classes in the MSDN documentation.
The expression #"[^\d]" also would work
I would basically create a static class that automatically pops up against any string.
If the same is GUID, you can simply do
Guid.NewGuid().ToString("N") returns only characters
Input: 12345678-1234-1234-1234-123456789abc
Output: 12345678123412341234123456789abc
public static string ToNonDashed(this string input)
{
return input?.Replace("-", string.Empty);
}
You can try this:
Des_AccNo = Des_AccNo.Replace("-", string.Empty);
string dash = Des_AccNo.ToString().Replace("-", string.Empty);
I have to validate a text box from a list of special characters that are not allowed.
This all are not allowed characters.
"&";"\";"/";"!";"%";"#";"^";"(";")";"?";"|";"~";"+";" ";
"{";"}";"*";",";"[";"]";"$";";";":";"=";"
Where semi-column is used to just separate between characters .I tried to write a regex for some characters to validate if it had worked i would extend it.it is not working .
What I am doing wrong in this.
Regex.IsMatch(textBox1.Text, #"^[\%\/\\\&\?\,\'\;\:\!\-]+$")
^[\%\/\\\&\?\,\'\;\:\!\-]+$
matches the strings that consist entirely of special characters. You need to invert the character class to match the strings that do not contain a special character:
^[^\%\/\\\&\?\,\'\;\:\!\-]+$
^--- added
Alternatively, you can use this regex to match any string containing only alphanumeric characters, hyphens, underscores and apostrophes.
^[a-zA-Z0-9\-'_]$
The regex you mention in the comments
[^a-zA-Z0-9-'_]
matches a string that contains any character except those that are allowed (you might need to escape the hyphen, though). This works as well, assuming you reverse the condition correctly (accept the strings that do not match).
If you are just looking for any of a list of characters then a regular expression is the more complicated option. String.IndexOfAny will return the first index of any of an array of characters or -1. So the check:
if (input.IndexOfAny(theCharacetrers) != -1) {
// Found one of them.
}
where theCharacetrers has previously been set up at class scope:
private readonly char[] theCharacetrers = new [] {'&','\','/','!','%','#','^',... };
You needed to remove ^ from the beginning and $ from the end of the pattern, otherwise in order to match the string should start and end with the special characters.
So, instead of
#"^[\%\/\\\&\?\,\'\;\:\!\-]+$"
it should be
#"[\%\/\\\&\?\,\'\;\:\!\-]+"
You can read more about start of string and end of string anchors here
Your RegExp is "string consiting only of special characters (since you have begin/end markers ^ and $).
You probably want just check if string does not contain any of the characters #"[\%\/\\\&\?\,\'\;\:\!\-]") would be enough.
Also String.IndexOfAny may be better fit if you just need to see if any of the characters is present in the source string.
PLease use this in textchange event
//Regex regex = new Regex("([a-zA-Z0-9 ._#]+)");
Regex regex = new Regex("^[a-zA-Z0-9_#(+).,-]+$");
string alltxt = txtOthers.Text;//txtOthers is textboxes name;
int k = alltxt.Length;
for (int i = 0; i <= k - 1; i++)
{
string lastch = alltxt.Substring(i, 1);
MatchCollection matches = regex.Matches(lastch);
if (matches.Count > 0)
{
}
else
{
txtOthers.Text = alltxt.Remove(i, 1);
i = i - 1;
alltxt = txtOthers.Text;
k = alltxt.Length;
}
txtOthers.Select(txtOthers.TextLength, 0);
}
BY Sharafu Hameed