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How to remove multiple, repeating & unnecessary punctuation from string in C#?

Considering strings like this:
"This is a string....!"
"This is another...!!"
"What is this..!?!?"
...
// There are LOTS of examples of weird/angry sentence-endings like the ones above.
I want to replace the unnecessary punctuation at the end to make it look like this:
"This is a string!"
"This is another!"
"What is this?"
What I basically do is:
- split by space
- check if last char in string contains a punctuation
- start replacing with the patterns below
I have tried a very big ".Replace(string, string)" function, but it does not work - there has to be a simpler regex I guess.
Documentation:
Returns a new string in which all occurrences of a specified string in the current instance are replaced with another specified string.
As well as:
Because this method returns the modified string, you can chain together successive calls to the Replace method to perform multiple replacements on the original string.
Anything is wrong here.
EDIT: ALL the proposed solutions work fine! Thank you very much!
This one was the best suited solution for my project:
Regex re = new Regex("[.?!]*(?=[.?!]$)");
string output = re.Replace(input, "");

Your solution works almost fine (demo), the only issue is when the same sequence could be matched starting at different spots. For example, ..!?!? from your last line is not part of the substitution list, so ..!? and !? get replaced by two separate matches, producing ?? in the output.
It looks like your strategy is pretty straightforward: in a chain of multiple punctuation characters the last character wins. You can use regular expressions to do the replacement:
[!?.]*([!?.])
and replace it with $1, i.e. the capturing group that has the last character:
string s;
while ((s = Console.ReadLine()) != null) {
s = Regex.Replace(s, "[!?.]*([!?.])", "$1");
Console.WriteLine(s);
}
Demo

Simply
[.?!]*(?=[.?!]$)
should do it for you. Like
Regex re = new Regex("[.?!]*(?=[.?!]$)");
Console.WriteLine(re.Replace("This is a string....!", ""));
This replaces all punctuations but the last with nothing.
[.?!]* matches any number of consecutive punctuation characters, and the (?=[.?!]$) is a positive lookahead making sure it leaves one at the end of the string.
See it here at ideone.

Or you can do it without regExps:
string TrimPuncMarks(string str)
{
HashSet<char> punctMarks = new HashSet<char>() {'.', '!', '?'};
int i = str.Length - 1;
for (; i >= 0; i--)
{
if (!punctMarks.Contains(str[i]))
break;
}
// the very last punct mark or null if there were no any punct marks in the end
char? suffix = i < str.Length - 1 ? str[str.Length - 1] : (char?)null;
return str.Substring(0, i+1) + suffix;
}
Debug.Assert("What is this?" == TrimPuncMarks("What is this..!?!?"));
Debug.Assert("What is this" == TrimPuncMarks("What is this"));
Debug.Assert("What is this." == TrimPuncMarks("What is this."));

Using regex to remove everything that is not in between '<#'something'#>' and replace it with commas

I have a string, for example
<#String1#> + <#String2#> , <#String3#> --<#String4#>
And I want to use regex/string manipulation to get the following result:
<#String1#>,<#String2#>,<#String3#>,<#String4#>
I don't really have any experience doing this, any tips?

There are multiple ways to do something like this, and it depends on exactly what you need. However, if you want to use a single regex operation to do it, and you only want to fix stuff that comes between the bracketed strings, then you could do this:
string input = "<#String1#> + <#String2#> , <#String3#> --<#String4#>";
string pattern = "(?<=>)[^<>]+(?=<)";
string replacement = ",";
string result = Regex.Replace(input, pattern, replacement);
The pattern uses [^<>]+ to match any non-pointy-bracket characters, but it combines it with a look-behind statement ((?<=>)) and a look-ahead statement (?=<) to make sure that it only matches text that occurs between a closing and another opening set of brackets.
If you need to remove text that comes before the first < or after the last >, or if you find the look-around statements confusing, you may want to consider simply matching the text that comes between the brackets and then loop through all the matches and build a new string yourself, rather than using the RegEx.Replace method. For instance:
string input = "sdfg<#String1#> + <#String2#> , <#String3#> --<#String4#>ag";
string pattern = #"<[^<>]+>";
List<String> values = new List<string>();
foreach (Match m in Regex.Matches(input, pattern))
values.Add(m.Value);
string result = String.Join(",", values);
Or, the same thing using LINQ:
string input = "sdfg<#String1#> + <#String2#> , <#String3#> --<#String4#>ag";
string pattern = #"<[^<>]+>";
string result = String.Join(",", Regex.Matches(input, pattern).Cast<Match>().Select(x => x.Value));

If you're just after string manipulation and don't necessarily need a regex, you could simply use the string.Replace method.
yourString = yourString.Replace("#> + <#", "#>,<#");

Using Regex.Replace to keep characters that can be vary

I have the following:
string text = "version=\"1,0\"";
I want to replace the comma for a dot, while keeping the 1 and 0, BUT keeping in mind that they be different in different situations! It could be version="2,3" .
The smart ass and noob-unworking way to do it would be:
for (int i = 0; i <= 9; i++)
{
for (int z = 0; z <= 9; z++)
{
text = Regex.Replace(text, "version=\"i,z\"", "version=\"i.z\"");
}
}
But of course.. it's a string, and I dont want i and z be behave as a string in there.
I could also try the lame but working way:
text = Regex.Replace(text, "version=\"1,", "version=\"1.");
text = Regex.Replace(text, "version=\"2,", "version=\"2.");
text = Regex.Replace(text, "version=\"3,", "version=\"3.");
And so on.. but it would be lame.
Any hints on how to single-handedly handle this?
Edit: I have other commas that I don't wanna replace, so text.Replace(",",".") can't do

You need a regex like this to locate the comma
Regex reg = new Regex("(version=\"[0-9]),([0-9]\")");
Then do the repacement:
text = reg.Replace(text, "$1.$2");
You can use $1, $2, etc. to refer to the matching groups in order.

(?<=version=")(\d+),
You can try this.See demo.Replace by $1.
https://regex101.com/r/sJ9gM7/52

You can perhaps use capture groups to keep the numbers in front and after for replacement afterwards for a more 'traditional way' to do it:
string text = "version=\"1,0\"";
var regex = new Regex(#"version=""(\d*),(\d*)""");
var result = regex.Replace(text, "version=\"$1.$2\"");
Using parens like the above in a regex is to create a capture group (so the matched part can be accessed later when needed) so that in the above, the digits before and after the comma will be stored in $1 and $2 respectively.
But I decided to delve a little bit further and let's consider the case if there are more than one comma to replace in the version, i.e. if the text was version="1,1,0". It would actually be tedious to do the above, and you would have to make one replace for each 'type' of version. So here's one solution that is sometimes called a callback in other languages (not a C# dev, but I fiddled around lambda functions and it seems to work :)):
private static string SpecialReplace(string text)
{
var result = text.Replace(',', '.');
return result;
}
public static void Main()
{
string text = "version=\"1,0,0\"";
var regex = new Regex(#"version=""[\d,]*""");
var result = regex.Replace(text, x => SpecialReplace(x.Value));
Console.WriteLine(result);
}
The above gives version="1.0.0".
"version=""[\d,]*""" will first match any sequence of digits and commas within version="...", then pass it to the next line for the replace.
The replace takes the matched text, passes it to the lambda function which takes it to the function SpecialReplace, where a simple text replace is carried out only on the matched part.
ideone demo

C# Regular Expression to return only the numbers

Let's say I have the following within my source code, and I want to return only the numbers within the string:
The source is coming from a website, just fyi, and I already have it parsed out so that it comes into the program, but then I need to actually parse these numbers to return what I want. Just having a doosy of a time trying to figure it out tho :(
like: 13|100|0;
How could I write this regex?
var cData = new Array(
"g;13|g;100|g;0",
"g;40|g;100|g;1.37",
"h;43|h;100|h;0",
"h;27|h;100|h;0",
"i;34|i;100|i;0",
"i;39|i;100|i;0",
);

Not sure you actually need regex here.
var str = "g;13|g;100|g;0";
str = str.Replace("g;", "");
would give you "13|100|0".
Or a slight improvement on spinon's answer:
// \- included in case numbers can be negative. Leave it out if not.
Regex.Replace("g;13|g;100|g;0", "[^0-9\|\.\-]", "");
Or an option using split and join:
String.Join("|", "g;13|g;100|g;0".Split('|').Select(pipe => pipe.Split(';')[1]));

I would use something like this so you only keep numbers and separator:
Regex.Replace("g;13|g;100|g;0", "[^0-9|]", "");

Regex might be overkill in this case. Given the uniform delimiting of | and ; I would recommend String.Split(). Then you could either split again or use String.Replace() to get rid of the extra chars (i.e. g;).

It looks like you have a number of solutions, but I'll throw in one more where you can iterate over each group in a match to get the number out if you want.
Regex regexObj = new Regex(#"\w;([\d|.]+)\|?");
Match matchResults = regexObj.Match("g;13|g;100|g;0");
if( matchResults.IsMatch )
{
for (int i = 1; i < matchResults.Groups.Count; i++)
{
Group groupObj = matchResults.Groups[i];
if (groupObj.Success)
{
//groupObj.Value will be the number you want
}
}
}
I hope this is helps.

Capitalizing words in a string using C#

I need to take a string, and capitalize words in it. Certain words ("in", "at", etc.), are not capitalized and are changed to lower case if encountered. The first word should always be capitalized. Last names like "McFly" are not in the current scope, so the same rule will apply to them - only first letter capitalized.
For example: "of mice and men By CNN" should be changed to "Of Mice and Men by CNN". (Therefore ToTitleString won't work here.)
What would be the best way to do that?
I thought of splitting the string by spaces, and go over each word, changing it if necessary, and concatenating it to the previous word, and so on.
It seems pretty naive and I was wondering if there's a better way to do it. I am using .NET 3.5.

Use
Thread.CurrentThread.CurrentCulture.TextInfo.ToTitleCase("of mice and men By CNN");
to convert to proper case and then you can loop through the keywords as you have mentioned.

Depending on how often you plan on doing the capitalization I'd go with the naive approach. You could possibly do it with a regular expression, but the fact that you don't want certain words capitalized makes that a little trickier.
You can do it with two passes using regular expressions:
var result = Regex.Replace("of mice and men isn't By CNN", #"\b(\w)", m => m.Value.ToUpper());
result = Regex.Replace(result, #"(\s(of|in|by|and)|\'[st])\b", m => m.Value.ToLower(), RegexOptions.IgnoreCase);
This outputs Of Mice and Men Isn't by CNN.
The first expression capitalizes every letter on a word boundary and the second one downcases any words matching the list that are surrounded by white space.
The downsides to this approach is that you're using regexs (now you have two problems) and you'll need to keep that list of excluded words up to date. My regex-fu isn't good enough to be able to do it in one expression, but it might be possible.

An answer from another question, How to Capitalize names -
CultureInfo cultureInfo = Thread.CurrentThread.CurrentCulture;
TextInfo textInfo = cultureInfo.TextInfo;
Console.WriteLine(textInfo.ToTitleCase(title));
Console.WriteLine(textInfo.ToLower(title));
Console.WriteLine(textInfo.ToUpper(title));

Use ToTitleCase() first and then keep a list of applicable words and Replace back to the all-lower-case version of those applicable words (provided that list is small).
The list of applicable words could be kept in a dictionary and looped through pretty efficiently, replacing with the .ToLower() equivalent.

Try something like this:
public static string TitleCase(string input, params string[] dontCapitalize) {
var split = input.Split(' ');
for(int i = 0; i < split.Length; i++)
split[i] = i == 0
? CapitalizeWord(split[i])
: dontCapitalize.Contains(split[i])
? split[i]
: CapitalizeWord(split[i]);
return string.Join(" ", split);
}
public static string CapitalizeWord(string word)
{
return char.ToUpper(word[0]) + word.Substring(1);
}
You can then later update the CapitalizeWord method if you need to handle complex surnames.
Add those methods to a class and use it like this:
SomeClass.TitleCase("a test is a sentence", "is", "a"); // returns "A Test is a Sentence"

A slight improvement on jonnii's answer:
var result = Regex.Replace(s.Trim(), #"\b(\w)", m => m.Value.ToUpper());
result = Regex.Replace(result, #"\s(of|in|by|and)\s", m => m.Value.ToLower(), RegexOptions.IgnoreCase);
result = result.Replace("'S", "'s");

You can have a Dictionary having the words you would like to ignore, split the sentence in phrases (.split(' ')) and for each phrase, check if the phrase exists in the dictionary, if it does not, capitalize the first character and then, add the string to a string buffer. If the phrase you are currently processing is in the dictionary, simply add it to the string buffer.

A non-clever approach that handles the simple case:
var s = "of mice and men By CNN";
var sa = s.Split(' ');
for (var i = 0; i < sa.Length; i++)
sa[i] = sa[i].Substring(0, 1).ToUpper() + sa[i].Substring(1);
var sout = string.Join(" ", sa);
Console.WriteLine(sout);

The easiest obvious solution (for English sentences) would be to:
"sentence".Split(" ") the sentence on space characters
Loop through each item
Capitalize the first letter of each item - item[i][0].ToUpper(),
Remerge back into a string joined on a space.
Repeat this process with "." and "," using that new string.

You should create your own function like you're describing.