how to remove special char from the string and make new string? - c#

I have a string 4(4X),4(4N),3(3X) from this string I want to make string 4,4,3. If I am getting the string 4(4N),3(3A),2(2X) then I want to make my string 4,3,2.
Please someone tell me how can I solve my problem.


This Linq query selects substring from each part of input string, starting from beginning till first open brace:
string input = "4(4N),3(3A),2(2X)";
string result = String.Join(",", input.Split(',')
.Select(s => s.Substring(0, s.IndexOf('('))));
// 4,3,2


This may help:
string inputString = "4(4X),4(4N),3(3X)";
string[] temp = inputString.Split(',');
List<string> result = new List<string>();
foreach (string item in temp)
{
result.Add(item.Split('(')[0]);
}
var whatYouNeed = string.Join(",", result);


You can use regular expressions
String input = #"4(4X),4(4N),3(3X)";
String pattern = #"(\d)\(\1.\)";
// ( ) - first group.
// \d - one number
// \( and \) - braces.
// \1 - means the repeat of first group.
String result = Regex.Replace(input, pattern, "$1");
// $1 means, that founded patterns will be replcaed by first group
//result = 4,4,3

Related

Regex - replacing chars in C# string in specific cases

I want to replace all brackets to another in my input string only when between them there aren't digits. I wrote this working sample of code:
string pattern = #"(\{[^0-9]*?\})";
MatchCollection matches = Regex.Matches(inputString, pattern);
if(matches != null)
{
foreach (var match in matches)
{
string outdateMatch = match.ToString();
string updateMatch = outdateMatch.Replace('{', '[').Replace('}', ']');
inputString = inputString.Replace(outdateMatch, updateMatch);
}
}
So for:
string inputString = "{0}/{something}/{1}/{other}/something"
The result will be:
inputString = "{0}/[something]/{1}/[other]/something"
Is there possibility to do this in one line using Regex.Replace() method?

You may use
var output = Regex.Replace(input, #"\{([^0-9{}]*)}", "[$1]");
See the regex demo.
Details
\{ - a { char
([^0-9{}]*) - Capturing group 1: 0 or more chars other than digits, { and }
} - a } char.
The replacement is [$1], the contents of Group 1 enclosed with square brackets.

Regex.Replace(input, #"\{0}/\{(.+)\}/\{1\}/\{(.+)}/(.+)", "{0}/[$1]/{1}/[$2]/$3")

Could you do this?
Regex.Replace(inputString, #"\{([^0-9]*)\}", "[$1]");
That is, capture the "number"-part, then just return the string with the braces replaced.
Not sure if this is exactly what you are after, but it seems to fit the question :)

Split constantly on the last delimiter in C#

I have the following string:
string x = "hello;there;;you;;;!;"
The result I want is a list of length four with the following substrings:
"hello"
"there;"
"you;;"
"!"
In other words, how do I split on the last occurrence when the delimiter is repeating multiple times? Thanks.

You need to use a regex based split:
var s = "hello;there;;you;;;!;";
var res = Regex.Split(s, #";(?!;)").Where(m => !string.IsNullOrEmpty(m));
Console.WriteLine(string.Join(", ", res));
// => hello, there;, you;;, !
See the C# demo
The ;(?!;) regex matches any ; that is not followed with ;.
To also avoid matching a ; at the end of the string (and thus keep it attached to the last item in the resulting list) use ;(?!;|$) where $ matches the end of string (can be replaced with \z if the very end of the string should be checked for).

It seems that you don't want to remove empty entries but keep the separators.
You can use this code:
string s = "hello;there;;you;;;!;";
MatchCollection matches = Regex.Matches(s, #"(.+?);(?!;)");
foreach(Match match in matches)
{
Console.WriteLine(match.Captures[0].Value);
}

string x = "hello;there;;you;;;!;"
var splitted = x.Split(new char[] { ';' }, StringSplitOptions.RemoveEmptryEntries);
foreach (var s in splitted)
Console.WriteLine("{0}", s);

Inserting Special character at specific length in a string

I want to insert - in between them at 4 digits interval in the given string. In the string there will be no special characters and it is a controller code.
string char = "123456789012"
I want answer
string char = "1234-5678-9012"

You can use Regex.Replace (combined with String.Trim to remove the trailing dash):
string str = "123456789012";
string res = Regex.Replace(str, #"\d{4}", match => match + "-").Trim('-');
Console.WriteLine(res); // 1234-5678-9012

As a non-regex alternative, you can use Batch from MoreLINQ like;
string s = "123456789012";
var list = s.Batch(4, seq => new string(seq.ToArray()));
Console.WriteLine(string.Join("-", list));
Prints
1234-5678-9012

How to remove the exact occurence of characters from a string?

For Example, I have a string like :
string str = "santhosh,phani,ravi,phani123,praveen,sathish,prakash";
I want to delete the charaters ,phani from str.
Now, I am using str = str.Replace(",phani", string.Empty);
then my output is : str="santhosh,ravi123,praveen,sathish,prakash";
But I want a output like : str="santhosh,ravi,phani123,praveen,sathish,prakash";

string str = "santhosh,phani,ravi,phani123,praveen,sathish,prakash";
var words = str.Split(',');
str = String.Join(",", words.Where(word => word != "phani"));

the better choice is to use a Split and Join method.
Easy in Linq :
String str = "santhosh,phani,ravi,phani123,praveen,sathish,prakash";
String token = "phani";
String result = String.Join(",", str.Split(',').Where(s => s != token));
(edit : I take time for testing and i'm not first ^^)

String.join(",", str.split(',').ToList().remove("phani"));
Removes any given name from the list.

How about
str = str.Replace(",phani,", ",");
This, however, does not work if "phani" is the last item in the string. To get around this, you could do this:
string source = "...";
source += ","; // Explicitly add a comma to the end
source = source.Replace(",phani,", ",").TrimEnd(',');
This adds a comma, replaces "phani" and removes the trailing comma.
A third solution would be this:
str = String.Join(",", str.Split(',').ToList().Remove("phani").ToArray());

Try to use with comma instead of;
string str = "santhosh,ravi,phani,phani123,praveen,sathish,prakash";
str = str.Replace(",phani,", ",");
Console.WriteLine(str);
Output will be;
santhosh,ravi,phani123,praveen,sathish,prakash
Here is a DEMO.
As Davin mentioned in comment, this won't work if phani is last item in the string. Silvermind's answer looks like the right answer.

string str = "santhosh,phani,ravi,phani123,praveen,sathish,prakash";
string pattern = #"\b,phani,\b";
string replace = ",";
Console.WriteLine(Regex.Replace(str, pattern, replace));
Output:
santhosh,ravi,phani123,praveen,sathish,prakash

You may use the regular expression, but you have to take care of cases when your string starts or ends with the substring:
var pattern = #",?\bphani\b,?";
var regex = new Regex(pattern);
var result = regex.Replace(input, ",").Trim(',');
Shorter notation could look like this:
var result = Regex.Replace(input, #",?\bphani\b,?", ",").Trim(',');
Explanation of the regular expression: ,?\bphani\b,? matches the word phani, but only if preceded and followed by word-delimiter characters (because of the word boundary metacharacter \b), and it can be (but doesn't have to be) preceded and followed by the comma thanks to ,? which means none or more comma(s).
At the end we need to remove possible commas from the beginning and end of the string, that's why there's Trim(',') on the result.

C# regex.split method is adding empty string before parenthesis

I have some code that tokenizes a equation input into a string array:
string infix = "( 5 + 2 ) * 3 + 4";
string[] tokens = tokenizer(infix, #"([\+\-\*\(\)\^\\])");
foreach (string s in tokens)
{
Console.WriteLine(s);
}
Now here is the tokenizer function:
public string[] tokenizer(string input, string splitExp)
{
string noWSpaceInput = Regex.Replace(input, #"\s", "");
Console.WriteLine(noWSpaceInput);
Regex RE = new Regex(splitExp);
return (RE.Split(noWSpaceInput));
}
When I run this, I get all characters split, but there is an empty string inserted before the parenthesis chracters...how do I remove this?
//empty string here
(
5
+
2
//empty string here
)
*
3
+
4

I would just filter them out:
public string[] tokenizer(string input, string splitExp)
{
string noWSpaceInput = Regex.Replace(input, #"\s", "");
Console.WriteLine(noWSpaceInput);
Regex RE = new Regex(splitExp);
return (RE.Split(noWSpaceInput)).Where(x => !string.IsNullOrEmpty(x)).ToArray();
}

What you're seeing is because you have nothing then a separator (i.e. at the beginning of the string is(), then two separator characters next to one another (i.e. )* in the middle). This is by design.
As you may have found with String.Split, that method has an optional enum which you can give to have it remove any empty entries, however, there is no such parameter with regular expressions. In your specific case you could simply ignore any token with a length of 0.
foreach (string s in tokens.Where(tt => tt.Length > 0))
{
Console.WriteLine(s);
}

Well, one option would be to filter them out afterwards:
return RE.Split(noWSpaceInput).Where(x => !string.IsNullOrEmpty(x)).ToArray();

Try this (if you don't want to filter the result):
tokenizer(infix, #"(?=[-+*()^\\])|(?<=[-+*()^\\])");
Perl demo:
perl -E "say join ',', split /(?=[-+*()^])|(?<=[-+*()^])/, '(5+2)*3+4'"
(,5,+,2,),*,3,+,4
Altho it would be better to use a match instead of split in this case imo.

I think you can use the [StringSplitOptions.RemoveEmptyEntries] by the split
static void Main(string[] args)
{
string infix = "( 5 + 2 ) * 3 + 4";
string[] results = infix.Split(" ".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
foreach (var result in results)
Console.WriteLine(result);
Console.ReadLine();
}

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