Develop Reference

Prepend/Append string for each element in a string array

I have some code as below:
char[] separator = { ',' };
String[] idList = m_idsFromRequest.Split(separator); //m_idsFromRequest="1,2....";
List<string> distinctIdList = idList.Distinct().ToList();
m_distinctIdList = distinctIdList.ToArray();
m_idsFromRequest = string.Join(" ", distinctIdList);
currently m_idsFromRequest = ["1","2".........."] is as such.
I want to make it ["0|1","0|2".........."] like append "0|" in each element . I wanted to know id I could do it without the foreach loop.

You can use Select and String.Join:
var idsPrependedWithZero = m_idsFromRequest.Split(separator)
.Distinct() // same as in your code
.Select(id => $"0|{id}");
string result = string.Join(",", idsPrependedWithZero);

char[] separator = { ',' };
string m_idsFromRequest = "1,2,3,4,5,6";
String[] idList = m_idsFromRequest.Split(separator); //m_idsFromRequest="1,2....";
List<string> distinctIdList = idList.Distinct().Select(t => "0|" + t).ToList();
m_idsFromRequest = string.Join(",", distinctIdList);
Just added the .Select() after .Distinct(). Inside the .Select you can transform each of the item in the list.
Apart from that i also added "," in your string.Join. Because you want it to be join by comma.

Check a pattern in a string then convert it to upper case

I was not clear with my previous question
I have a list: new List<string> { "lts", "mts", "cwts", "rotc" };
Now I wan't to check a pattern in string that starts or ends with a forward slash like this: "cTws/Rotc/lTs" or "SomethingcTws cWtS/Rotc rOtc".
and convert to upper case only the string that starts/ends with a forward slash based on the list that I have.
So the output should be: "CWTS/ROTC/LTS", "SomethingcTws CWTS/ROTC rOtc"
I modified Sachin's answer:
List<string> replacementValues = new List<string>
{
"cwts",
"mts",
"rotc",
"lts"
};
string pattern = string.Format(#"\G({0})/?", string.Join("|", replacementValues.Select(x => Regex.Escape(x))));
Regex regExp = new Regex(pattern, RegexOptions.IgnoreCase);
string value = "Cwts/Rotc Somethingcwts1 Cwts/Rotc/lTs";
string result = regExp.Replace(value, s => s.Value.ToUpper());
Result: CWTS/ROTC Somethingcwts1 Cwts/Rotc/lTs
The desired output should be: CWTS/ROTC Somethingcwts1 CWTS/ROTC/LTS

So instead of using Regex, which I'm not really good with, I'm doing split by space then split by "/" then rejoin the strings
string val = "Somethingrotc1 cWts/rOtC/lTs Cwts";
List<string> replacementValues = new List<string>
{
"lts", "mts",
"cwts", "rotc"
};
string[] tokens = val.Split(new char[] { ' ' }, StringSplitOptions.None);
string result = string.Join(" ", tokens.Select(t =>
{
// Now split by "/"
string[] ts = t.Split(new char[] { '/' }, StringSplitOptions.None);
if (ts.Length > 1)
{
t = string.Join("/", ts.Select(x => replacementValues.Contains(x.ToLower()) ? x.ToUpper() : x));
}
return t;
}));
Output: Somethingrotc1 CWTS/ROTC/LTS Cwts

You want to change the specific words in the string to Upper case. Then you can use Regex to achieve it.
string value = "Somethingg1 Cwts/Rotc/Lts Cwts";
var replacementValues = new Dictionary<string, string>()
{
{"Cwts","CWTS"},
{"Rotc","ROTC"},
{"Lts","LTC"}
};
var regExpression = new Regex(String.Join("|", replacementValues.Keys.Select(x => Regex.Escape(x))));
var outputString = regExpression.Replace(value, s => replacementValues[s.Value]);

Remove specific symbol from string

I have different string that starts and ends with { } like so {somestring}. I want to remove the delimiters from the string so that it shows somestring only. I can't do anything that counts the letters because I don't always know the length of the string.
Maybe this will help. Here is the code, somewhere here I want to delete the delimiters.
private static MvcHtmlString RenderDropDownList(FieldModel model)
{
ISerializer serializer = new SerializeJSon();
var value = "";
var tb1 = new TagBuilder("select");
tb1.MergeAttribute("id", model.QuestionId);
tb1.MergeAttribute("name", model.QuestionId);
tb1.MergeAttributes(GetHtmlAttributes(model.HtmlAttributes));
tb1.AddCssClass("form-field");
var sb = new StringBuilder();
MatchCollection matches = RegexHelper.GetBetweenDelimiter(model.FieldValues, "{", "}");
foreach (Match match in matches)
{
var o = match; //Solution var o = match.toString();
var tb2 = new TagBuilder("option");
//Solution string newString = o.trim(new [] { "{","}"});
tb2.SetInnerText(o.ToString()); //Solution tb2.SetInnerText(newString);
sb.Append(tb2.ToString(TagRenderMode.Normal) + "\n");
}
tb1.InnerHtml = sb.ToString();
return new MvcHtmlString(tb1.ToString(TagRenderMode.Normal));
}

string newString = originalString.Trim(new[] {'{', '}'});

Can you use Replace
string somestring = somestring.Replace("{","").Replace("}","");
Alternatively, you can use StartsWith and EndsWith which will only remove from the beginning and the end of the string, for example:
string foo = "{something}";
if (foo.StartsWith("{"))
{
foo = foo.Remove(0, 1);
}
if (foo.EndsWith("}"))
{
foo = foo.Remove(foo.Length-1, 1);
}

You could use replace e.g.
string someString = "{somestring}";
string someOtherString = someString.Replace("{","").Replace("}","");

Filtering comma separated String in C#

I have a dynamic String value which may contain values like this
"Apple ,Banana, , , , Mango ,Strawberry , "
I would like to filter this string like
"Apple,Banana,Mango,Strawberry".
I have tried with the following code and it works.
Is there any better approach to achieve the same in C#(.NET 2.0)?
/// <summary>
/// Convert "Comma Separated String" to "Comma Separated String"
/// </summary>
/// <param name="strWithComma">String having values separated by comma</param>
/// <returns>String separated with comma</returns>
private String CommaSeparatedString(String strWithComma)
{
String rtn = String.Empty;
List<String> newList= new List<string>();
if (String.IsNullOrEmpty(strWithComma))
{
return rtn;
}
String[] strArray = strWithComma.Split(",".ToCharArray());
if (strArray == null || strArray.Length == 0)
{
return rtn;
}
String tmpStr = String.Empty;
String separator=String.Empty;
foreach (String s in strArray)
{
if (!String.IsNullOrEmpty(s))
{
tmpStr =s.Replace(Environment.NewLine, String.Empty);
tmpStr = tmpStr.Trim();
if (!String.IsNullOrEmpty(tmpStr))
{
newList.Add(tmpStr);
}
}
}
if (newList != null && newList.Count > 0)
{
rtn = String.Join(",", newList.ToArray());
}
return rtn;
}

you can also use Regex:
string str = #"Apple ,,Banana, , , , Mango ,Strawberry , ";
string result = Regex.Replace(str, #"(\s*,\s*)+", ",").TrimEnd(',');

I believe the following should do the trick on any .NET version:
string[] TrimAll( string[] input )
{
var result = new List<string>();
foreach( var s in input )
result.Add( s.Trim() );
}
return result.ToArray();
}
var delimiters = new [] { ",", "\t", Environment.NewLine };
string result = string.Join(",", TrimAll( input.Split( delimiters, StringSplitOptions.RemoveEmptyEntries ) ) );
Edit: updated to deal with white-space, tabs and newline.

Assuming that your items do not contain spaces:
private String CommaSeparatedString(String strWithComma)
{
string[] tokens = strWithComma
.Replace(" ", "")
.Split(new char[] {','}, StringSplitOptions.RemoveEmptyEntries);
return string.Join(",", tokens);
}
Now I'm not sure if C# 2.0 accepts the new char[] {','} syntax. If not, you can define the array somewhere else (as a class private member, for example).

Here's a one-liner:
var outputString = string.Join(",", inputString.Replace(" ", string.Empty).Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries));

Regex regex = new Regex(#"\w(?:(?!,| ).)*");
var items = regex.Matches("Apple ,Banana, , , , Mango ,Strawberry , ").Cast<Match>().Select(m => m.Value);
.NET 2.0 Version
List<string> newList = new List<string>();
Regex regex = new Regex(#"\w(?:(?!,| ).)*");
string str = "Apple ,Banana, , , , Mango ,Strawberry , ";
MatchCollection matches = regex.Matches(str);
foreach (Match match in matches)
{
newList.Add(match.Value);
}

var result = Regex.Replace(strWithComma, ",+", ",").TimEnd(',');
result = Regex.Replace(result, "\s+", string.Empty);

With no regular expressions, no splits and joins, trims, etc, O(n) time. StringBuilder is a very good class to work with strings.
EDIT
If the string it doesn't end with a letter it will add a comma. So an extra TrimEnd(',') is added
string strWithComma = ",Apple ,Banana, , , , Mango ,Strawberry , \n John,";
var sb = new StringBuilder();
var addComma = false;
foreach (var c in strWithComma )
{
if (Char.IsLetter(c)) // you might want to allow the dash also: example Anne-Marie
{
addComma = true;
sb.Append(c);
}
else
{
if (addComma)
{
addComma = false;
sb.Append(',');
}
}
}
string rtn = sb.ToString().TrimEnd(',');

Warning this method will only apply for C# 3.0 or higher. Sorry guys didnt read the question well enough
This will work but it can be done much easier like:
string input = "apple,banana,, \n,test\n, ,juice";
var parts = from part in input.Split(',')
let trimmedPart = part.Replace("\n", "")
where !string.IsNullOrWhiteSpace(trimmedPart)
select trimmedPart;
string result = string.Join(",", parts);

Join collection of objects into comma-separated string

In many places in our code we have collections of objects, from which we need to create a comma-separated list. The type of collection varies: it may be a DataTable from which we need a certain column, or a List<Customer>, etc.
Now we loop through the collection and use string concatenation, for example:
string text = "";
string separator = "";
foreach (DataRow row in table.Rows)
{
text += separator + row["title"];
separator = ", ";
}
Is there a better pattern for this? Ideally I would like an approach we could reuse by just sending in a function to get the right field/property/column from each object.

string.Join(", ", Array.ConvertAll(somelist.ToArray(), i => i.ToString()))

static string ToCsv<T>(IEnumerable<T> things, Func<T, string> toStringMethod)
{
StringBuilder sb = new StringBuilder();
foreach (T thing in things)
sb.Append(toStringMethod(thing)).Append(',');
return sb.ToString(0, sb.Length - 1); //remove trailing ,
}
Use like this:
DataTable dt = ...; //datatable with some data
Console.WriteLine(ToCsv(dt.Rows, row => row["ColName"]));
or:
List<Customer> customers = ...; //assume Customer has a Name property
Console.WriteLine(ToCsv(customers, c => c.Name));
I don't have a compiler to hand but in theory it should work. And as everyone knows, in theory, practice and theory are the same. In practice, they're not.

I found string.Join and lambda Select<Func<>> helps to write minimum code.
List<string> fruits = new List<string>();
fruits.Add("Mango");
fruits.Add("Banana");
fruits.Add("Papaya");
string commaSepFruits = string.Join(",", fruits.Select(f => "'" + f + "'"));
Console.WriteLine(commaSepFruits);
List<int> ids = new List<int>();
ids.Add(1001);
ids.Add(1002);
ids.Add(1003);
string commaSepIds = string.Join(",", ids);
Console.WriteLine(commaSepIds);
List<Customer> customers = new List<Customer>();
customers.Add(new Customer { Id = 10001, Name = "John" });
customers.Add(new Customer { Id = 10002, Name = "Robert" });
customers.Add(new Customer { Id = 10002, Name = "Ryan" });
string commaSepCustIds = string.Join(", ", customers.Select(cust => cust.Id));
string commaSepCustNames = string.Join(", ", customers.Select(cust => "'" + cust.Name + "'"));
Console.WriteLine(commaSepCustIds);
Console.WriteLine(commaSepCustNames);
Console.ReadLine();

// using System.Collections;
// using System.Collections.Generic;
// using System.Linq
public delegate string Indexer<T>(T obj);
public static string concatenate<T>(IEnumerable<T> collection, Indexer<T> indexer, char separator)
{
StringBuilder sb = new StringBuilder();
foreach (T t in collection) sb.Append(indexer(t)).Append(separator);
return sb.Remove(sb.Length - 1, 1).ToString();
}
// version for non-generic collections
public static string concatenate<T>(IEnumerable collection, Indexer<T> indexer, char separator)
{
StringBuilder sb = new StringBuilder();
foreach (object t in collection) sb.Append(indexer((T)t)).Append(separator);
return sb.Remove(sb.Length - 1, 1).ToString();
}
// example 1: simple int list
string getAllInts(IEnumerable<int> listOfInts)
{
return concatenate<int>(listOfInts, Convert.ToString, ',');
}
// example 2: DataTable.Rows
string getTitle(DataRow row) { return row["title"].ToString(); }
string getAllTitles(DataTable table)
{
return concatenate<DataRow>(table.Rows, getTitle, '\n');
}
// example 3: DataTable.Rows without Indexer function
string getAllTitles(DataTable table)
{
return concatenate<DataRow>(table.Rows, r => r["title"].ToString(), '\n');
}

In .NET 4 you can just do string.Join(", ", table.Rows.Select(r => r["title"]))

You could write a function that transforms a IEnumerable<string> into a comma-separated string:
public string Concat(IEnumerable<string> stringList)
{
StringBuilder textBuilder = new StringBuilder();
string separator = String.Empty;
foreach(string item in stringList)
{
textBuilder.Append(separator);
textBuilder.Append(item);
separator = ", ";
}
return textBuilder.ToString();
}
You can then use LINQ to query your collection/dataset/etc to provide the stringList.

As an aside: The first modification I would make is to use the StringBuilder Class instead of just a String - it'll save resources for you.

I love Matt Howells answer in this post:
I had to make it into an extension:
public static string ToCsv<T>(this IEnumerable<T> things, Func<T, string> toStringMethod)
Usage (I am getting all the emails and turning them into a CSV string for emails):
var list = Session.Find("from User u where u.IsActive = true").Cast<User>();
return list.ToCsv(i => i.Email);

For collections you can use this method as well, for example:
string.Join(", ", contactsCollection.Select(i => i.FirstName));
You can select any property that you want to separate.

string strTest = "1,2,4,6";
string[] Nums = strTest.Split(',');
Console.Write(Nums.Aggregate<string>((first, second) => first + "," + second));
//OUTPUT:
//1,2,4,6

Here's my favorite answer adapted to the question,
and corrected Convert to ConvertAll:
string text = string.Join(", ", Array.ConvertAll(table.Rows.ToArray(), i => i["title"]));