Develop Reference

Delete string from a double in C#

I am sending data from arduino to c# and have a problem. The value I get from the serialread comes with an "\r" at the end of it, example: "19.42\r". I found a solution to delete the characters after my number by using Regex. But it also makes my double an integer. "19.42\r" becomes "1942". How can I delete my string but still keep the value as a double?
line = Regex.Replace(line, #"[^\d]", string.Empty);

You want to trim the whitespace from the end of the string.
Use
line = line.TrimEnd();
See the C# demo
If you need to actually extract a double number from a string with regex, use
var my_number = string.Empty;
var match = Regex.Match(line, #"[0-9]+\.[0-9]+");
if (match.Success)
{
my_number = match.Value;
}
If the number can have no fractional part, use #"[0-9]*\.?[0-9]+" regex.

string data = "19.42\r";
return data.Substring(0, data.Length - 1);
or even better
data.TrimEnd('\r')

if \r is fixed characters you want to remove
string str = "awdawdaw\r";
str = str.replace("\r","");
if \r is not fixed characters you want to remove
string str = "awdawdaw\\";
str = str.Substring((str.Length - 2), 2); \\will be removed

3-digit grouping of all numbers in an alphanumeric string

I found it not efficient to iterate through string parts split by space character and extract numeric parts and apply
UInt64.Parse(Regex.Match(numericPart, #"\d+").Value)
and the concatenating them together to form the string with numbers being grouped.
Is there a better, more efficient way to 3-digit grouping of all numbers in an string containing other characters?

I am pretty sure the most efficient way (CPU-wise, with just a single pass over the string) is the basic foreach loop, along these lines
var sb = new StringBuilder()
foreach(char c in inputString)
{
// if c is a digit count
// else reset counter
// if there are three digits insert a "."
}
return sb.ToString()
This will produce 123.456.7
If you want 1.234.567 you'll need an additional buffer for digit-sequences

So you want to replace all longs in a string with the same long but with a number-group-separator of the current culture? .... Yes
string[] words = input.Split();
var newWords = words.Select(w =>
{
long l;
bool isLong = System.Int64.TryParse(w.Trim(), out l);
if(isLong)
return l.ToString("N0");
else
return w;
});
string result = string.Join(" ", newWords);
With the input from your comment:
string input = "hello 134443 in the 33 when 88763 then";
You get the expected result: "hello 134,443 in the 33 when 88,763 then", if your current culture uses comma as number-group-separator.

I will post my regex-based example. I believe regex does not have to be too slow, especially once it is compiled and is declared with static and readonly.
// Declare the regex
private static readonly Regex regex = new Regex(#"(\d)(?=(\d{3})+(?!\d))", RegexOptions.Compiled);
// Then, somewhere inside a method
var replacement = string.Format("$1{0}", System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberGroupSeparator); // Get the system digit grouping separator
var strn = "Hello 34234456 where 3334 is it?"; // Just a sample string
// Somewhere (?:inside a loop)?
var res = regex.Replace(strn, replacement);
Output (if , is a system digit grouping separator):
Hello 34,234,456 where 3,334 is it?

Omit unnecessary parts in string array

In C#, I have a string comes from a file in this format:
Type="Data"><Path.Style><Style
or maybe
Type="Program"><Rectangle.Style><Style
,etc. Now I want to only extract the Data or Program part of the Type element. For that, I used the following code:
string output;
var pair = inputKeyValue.Split('=');
if (pair[0] == "Type")
{
output = pair[1].Trim('"');
}
But it gives me this result:
output=Data><Path.Style><Style
What I want is:
output=Data
How to do that?

This code example takes an input string, splits by double quotes, and takes only the first 2 items, then joins them together to create your final string.
string input = "Type=\"Data\"><Path.Style><Style";
var parts = input
.Split('"')
.Take(2);
string output = string.Join("", parts); //note: .net 4 or higher
This will make output have the value:
Type=Data
If you only want output to be "Data", then do
var parts = input
.Split('"')
.Skip(1)
.Take(1);
or
var output = input
.Split('"')[1];

What you can do is use a very simple regular express to parse out the bits that you want, in your case you want something that looks like this and then grab the two groups that interest you:
(Type)="(\w+)"
Which would return in groups 1 and 2 the values Type and the non-space characters contained between the double-quotes.

Instead of doing many split, why don't you just use Regex :
output = Regex.Match(pair[1].Trim('"'), "\"(\w*)\"").Value;

Maybe I missed something, but what about this:
var str = "Type=\"Program\"><Rectangle.Style><Style";
var splitted = str.Split('"');
var type = splitted[1]; // IE Data or Progam
But you will need some error handling as well.

How about a regex?
var regex = new Regex("(?<=^Type=\").*?(?=\")");
var output = regex.Match(input).Value;
Explaination of regex
(?<=^Type=\") This a prefix match. Its not included in the result but will only match
if the string starts with Type="
.*? Non greedy match. Match as many characters as you can until
(?=\") This is a suffix match. It's not included in the result but will only match if the next character is "

Given your specified format:
Type="Program"><Rectangle.Style><Style
It seems logical to me to include the quote mark (") when splitting the strings... then you just have to detect the end quote mark and subtract the contents. You can use LinQ to do this:
string code = "Type=\"Program\"><Rectangle.Style><Style";
string[] parts = code.Split(new string[] { "=\"" }, StringSplitOptions.None);
string[] wantedParts = parts.Where(p => p.Contains("\"")).
Select(p => p.Substring(0, p.IndexOf("\""))).ToArray();

replacing characters in a single field of a comma-separated list

I have string in my c# code
a,b,c,d,"e,f",g,h
I want to replace "e,f" with "e f" i.e. ',' which is inside inverted comma should be replaced by space.
I tried using string.split but it is not working for me.

OK, I can't be bothered to think of a regex approach so I am going to offer an old fashioned loop approach which will work:
string DoReplace(string input)
{
bool isInner = false;//flag to detect if we are in the inner string or not
string result = "";//result to return
foreach(char c in input)//loop each character in the input string
{
if(isInner && c == ',')//if we are in an inner string and it is a comma, append space
result += " ";
else//otherwise append the character
result += c;
if(c == '"')//if we have hit an inner quote, toggle the flag
isInner = !isInner;
}
return result;
}
NOTE: This solution assumes that there can only be one level of inner quotes, for example you cannot have "a,b,c,"d,e,"f,g",h",i,j" - because that's just plain madness!

For the scenario where you only need to match one pair of letters, the following regex will work:
string source = "a,b,c,d,\"e,f\",g,h";
string pattern = "\"([\\w]),([\\w])\"";
string replace = "\"$1 $2\"";
string result = Regex.Replace(source, pattern, replace);
Console.WriteLine(result); // a,b,c,d,"e f",g,h
Breaking apart the pattern, it is matching any instance where there is a "X,X" sequence where X is any letter, and is replacing it with the very same sequence, with a space in between the letters instead of a comma.
You could easily extend this if you needed to to have it match more than one letter, etc, as needed.
For the case where you can have multiple letters separated by commas within quotes that need to be replaced, the following can do it for you. Sample text is a,b,c,d,"e,f,a",g,h:
string source = "a,b,c,d,\"e,f,a\",g,h";
string pattern = "\"([ ,\\w]+),([ ,\\w]+)\"";
string replace = "\"$1 $2\"";
string result = source;
while (Regex.IsMatch(result, pattern)) {
result = Regex.Replace(result, pattern, replace);
}
Console.WriteLine(result); // a,b,c,d,"e f a",g,h
This does something similar compared to the first one, but just removes any comma that is sandwiched by letters surrounded by quotes, and repeats it until all cases are removed.

Here's a somewhat fragile but simple solution:
string.Join("\"", line.Split('"').Select((s, i) => i % 2 == 0 ? s : s.Replace(",", " ")))
It's fragile because it doesn't handle flavors of CSV that escape double-quotes inside double-quotes.

Use the following code:
string str = "a,b,c,d,\"e,f\",g,h";
string[] str2 = str.Split('\"');
var str3 = str2.Select(p => ((p.StartsWith(",") || p.EndsWith(",")) ? p : p.Replace(',', ' '))).ToList();
str = string.Join("", str3);

Use Split() and Join():
string input = "a,b,c,d,\"e,f\",g,h";
string[] pieces = input.Split('"');
for ( int i = 1; i < pieces.Length; i += 2 )
{
pieces[i] = string.Join(" ", pieces[i].Split(','));
}
string output = string.Join("\"", pieces);
Console.WriteLine(output);
// output: a,b,c,d,"e f",g,h

best possible way to get given substring

lets say I have string in format as below:
[val1].[val2].[val3] ...
What is the best way to get the value from the last bracket set [valx] ?
so for given example
[val1].[val2].[val3]
the result would be val3

You have to define best first, best in terms of readability or cpu-cycles?
I assume this is efficient and readable enough:
string values = "[val1].[val2].[val3]";
string lastValue = values.Split('.').Last().Trim('[',']');
or with Substring which can be more efficient, but it's not as safe since you have to handle the case that's there no dot at all.
lastValue = values.Substring(values.LastIndexOf('.') + 1).Trim('[',']');
So you need to check this first:
int indexOflastDot = values.LastIndexOf('.');
if(indexOflastDot >= 0)
{
lastValue = values.Substring(indexOflastDot + 1).Trim('[',']');
}

For a quick solution to your problem (so not structural),
I'd say:
var startIndex = input.LastIndexOf(".["); // getting the last
then using the Substring method
var value = input.Substring(startIndex + 2, input.Length - (startIndex - 2)); // 2 comes from the length of ".[".
then removing the "]" with TrimEnd function
var value = value.TrimEnd(']');
But this is by all means not the only solution, and not structural to apply.. Just one of many answers to your problem.

I think you want to access the valx.
The easiest solution that comes in my mind is this one:
public void Test()
{
var splitted = "[val1].[val2].[val3]".Split('.');
var val3 = splitted[2];
}

You can use following:
string[] myStrings = ("[val1].[val2].[val3]").Split('.');
Now you can access via index. For last you can use myStrings[myStrings.length - 1]

Providing, that none of val1...valN contains '.', '[' or ']' you can use a simple Linq code:
String str = #"[val1].[val2].[val3]";
String[] vals = str.Split('.').Select((x) => x.TrimStart('[').TrimEnd(']')).ToArray();
Or if all you want is the last value:
String str = #"[val1].[val2].[val3]";
String last = str.Split('.').Last().TrimStart('[').TrimEnd(']');

I'm assuming you always need the last brace. I would do it like this:
string input = "[val1].[val2].[val3]";
string[] splittedInput = input.split('.');
string lastBraceSet = splittedInput[splittedInput.length-1];
string result = lastBraceSet.Substring(1, lastBraceSet.Length - 2);

string str = "[val1].[val2].[val3]";
string last = str.Split('.').LastOrDefault();
string result = last.Replace("[", "").Replace("]", "");

string input="[val1].[val2].[val3]";
int startpoint=input.LastIndexOf("[")+1;
string result=input.Substring(startpoint,input.Length-startpoint-1);

I'd use the below regex. One warning is that it won't work if there are unbalanced square brackets after the last pair of brackets. Most of the answers given suffer from that though.
string s = "[val1].[val2].[val3]"
string pattern = #"(?<=\[)[^\]]+(?=\][^\[\]]*$)"
Match m = Regex.Match(s, pattern)
string result;
if (m.Success)
{
result = m.Value;
}

I would use regular expression, as they are the most clear from intention point of view:
string input = "[val1].[val2].[val3] ...";
string match = Regex.Matches(input, #"\[val\d+\]")
.Cast<Match>()
.Select(m => m.Value)
.Last();