Creating a comma separated list from IList string or IEnumerable string

Question

What is the cleanest way to create a comma-separated list of string values from an IList lt string gt  or IEnumerable lt string gt    String Join      operates on a string   so can be cumbersome to work with when types such as IList lt string gt  or IEnumerable lt string gt  cannot easily be converted into a string array

User · Answer

If the strings you want to join are in List of Objects  then you can do something like this too   var studentNames   string Join       students Select x   gt  x name

User · Answer

Specific need when we should surround by    by ex            string   arr      jj    laa    123             List lt string gt  myList   arr ToList                 jj    laa    123          Console WriteLine string Join                   myList ConvertAll m   gt                  string Format    0     m   ToArray

User · Answer

You can use  ToArray   on Lists and IEnumerables  and then use String Join   as you wanted

User · Answer

Here s the way I did it  using the way I have done it in other languages   private string ToStringList lt T gt  IEnumerable lt T gt  list  string delimiter      var sb   new StringBuilder      string separator   String Empty    foreach  T value in list          sb Append separator  Append value       separator   delimiter        return sb ToString

User · Answer

Arriving a little late to this discussion but this is my contribution fwiw  I have an IList lt Guid gt  OrderIds to be converted to a CSV string but following is generic and works unmodified with other types   string csv   OrderIds Aggregate new StringBuilder                  sb  v    gt  sb Append v  Append                    sb   gt   if  0  lt  sb Length  sb Length--  return sb ToString         Short and sweet  uses StringBuilder for constructing new string  shrinks StringBuilder length by one to remove last comma and returns CSV string   I ve updated this to use multiple Append   s to add string   comma  From James  feedback I used Reflector to have a look at StringBuilder AppendFormat    Turns out AppendFormat   uses a StringBuilder to construct the format string which makes it less efficient in this context than just using multiple Appends   s

User · Answer

They can be easily converted to an array using the Linq extensions in  NET 3 5      var stringArray   stringList ToArray

User · Answer

NET 4   IList lt string gt  strings   new List lt string gt   1   2   testing    string joined   string Join      strings     Detail  amp  Pre  Net 4 0 Solutions  IEnumerable lt string gt  can be converted into a string array very easily with LINQ   NET 3 5    IEnumerable lt string gt  strings        string   array   strings ToArray      It s easy enough to write the equivalent helper method if you need to   public static T   ToArray IEnumerable lt T gt  source        return new List lt T gt  source  ToArray        Then call it like this   IEnumerable lt string gt  strings        string   array   Helpers ToArray strings     You can then call string Join  Of course  you don t have to use a helper method      C  3 and  NET 3 5 way  string joined   string Join      strings ToArray        C  2 and  NET 2 0 way  string joined   string Join      new List lt string gt  strings  ToArray       The latter is a bit of a mouthful though     This is likely to be the simplest way to do it  and quite performant as well - there are other questions about exactly what the performance is like  including  but not limited to  this one   As of  NET 4 0  there are more overloads available in string Join  so you can actually just write   string joined   string Join      strings     Much simpler

User · Answer

Something a bit fugly  but it works   string divisionsCSV   String Join        List lt IDivisionView gt  divisions  ConvertAll lt string gt  d   gt  d DivisionID ToString  b    ToArray       Gives you a CSV from a List after you give it the convertor  in this case d    d DivisionID ToString  b      Hacky but works - could be made into an extension method perhaps

User · Answer

Hopefully this is the simplest way    string Commaseplist   string   itemList      Test1    Test2    Test3      Commaseplist   string join     itemList    Console WriteLine Commaseplist     Outputs Test1 Test2 Test3

User · Answer

I just solved this issue before happening across this article  My solution goes something like below       private static string GetSeparator lt T gt  IList lt T gt  list  T item              return  list IndexOf item     list Count - 1                      Called like   List lt thing gt  myThings  string tidyString   foreach  var thing in myThings         tidyString    string format  Thing  0  is a  1    thing id  thing name    GetSeparator myThings  thing       I could also have just as easily expressed as such and would have also been more efficient   string Join          myThings Select t   gt  string format    Thing  0  is a  1      t id  t name

User · Answer

My answer is like above Aggregate solution but should be less call-stack heavy since there are no explicit delegate calls   public static string ToCommaDelimitedString lt T gt  this IEnumerable lt T gt  items        StringBuilder sb   new StringBuilder        foreach  var item in items                sb Append item ToString             sb Append                 if  sb Length  gt   1  sb Length--      return sb ToString        Of course  one can extend the signature to be delimiter-independent  I m really not a fan of the sb Remove   call and I d like to refactor it to be a straight-up while-loop over an IEnumerable and use MoveNext   to determine whether or not to write a comma  I ll fiddle around and post that solution if I come upon it     Here s what I wanted initially   public static string ToDelimitedString lt T gt  this IEnumerable lt T gt  source  string delimiter  Func lt T  string gt  converter        StringBuilder sb   new StringBuilder        var en   source GetEnumerator        bool notdone   en MoveNext        while  notdone                sb Append converter en Current            notdone   en MoveNext            if  notdone  sb Append delimiter             return sb ToString        No temporary array or list storage required and no StringBuilder Remove   or Length-- hack required   In my framework library I made a few variations on this method signature  every combination of including the delimiter and the converter parameters with usage of     and x ToString   as defaults  respectively

User · Answer

Comparing by performance the winner is  Loop it  sb Append it  and do back step   Actually  enumerable and manual move next  is the same good  consider stddev    BenchmarkDotNet v0 10 5  OS Windows 10 0 14393 Processor Intel Core i5-2500K CPU 3 30GHz  Sandy Bridge   ProcessorCount 4 Frequency 3233539 Hz  Resolution 309 2587 ns  Timer TSC    Host    Clr 4 0 30319 42000  64bit RyuJIT-v4 6 1637 0   Clr      Clr 4 0 30319 42000  64bit RyuJIT-v4 6 1637 0   Core      NET Core 4 6 25009 03  64bit RyuJIT                   Method    Job   Runtime       Mean       Error      StdDev        Min        Max     Median   Rank    Gen 0   Allocated   ----------------------  -----  --------  ---------  ----------  ----------  ---------  ---------  ---------  -----  -------  ----------               StringJoin    Clr       Clr   28 24 us   0 4381 us   0 3659 us   27 68 us   29 10 us   28 21 us      8   4 9969     16 3 kB    SeparatorSubstitution    Clr       Clr   17 90 us   0 2900 us   0 2712 us   17 55 us   18 37 us   17 80 us      6   4 9296    16 27 kB        SeparatorStepBack    Clr       Clr   16 81 us   0 1289 us   0 1206 us   16 64 us   17 05 us   16 81 us      2   4 9459    16 27 kB               Enumerable    Clr       Clr   17 27 us   0 0736 us   0 0615 us   17 17 us   17 36 us   17 29 us      4   4 9377    16 27 kB               StringJoin   Core      Core   27 51 us   0 5340 us   0 4995 us   26 80 us   28 25 us   27 51 us      7   5 0296    16 26 kB    SeparatorSubstitution   Core      Core   17 37 us   0 1664 us   0 1557 us   17 15 us   17 68 us   17 39 us      5   4 9622    16 22 kB        SeparatorStepBack   Core      Core   15 65 us   0 1545 us   0 1290 us   15 45 us   15 82 us   15 66 us      1   4 9622    16 22 kB               Enumerable   Core      Core   17 00 us   0 0905 us   0 0654 us   16 93 us   17 12 us   16 98 us      3   4 9622    16 22 kB     Code   public class BenchmarkStringUnion       List lt string gt  testData   new List lt string gt         public BenchmarkStringUnion                 for int i 0 i lt 1000 i                          testData Add i ToString                          Benchmark      public string StringJoin                 var text   string Join lt string gt       testData           return text             Benchmark      public string SeparatorSubstitution                 var sb   new StringBuilder            var separator   String Empty          foreach  var value in testData                        sb Append separator  Append value               separator                          return sb ToString                Benchmark      public string SeparatorStepBack                 var sb   new StringBuilder            foreach  var item in testData              sb Append item  Append               if  sb Length gt  1               sb Length--          return sb ToString                Benchmark      public string Enumerable                 var sb   new StringBuilder            var e   testData GetEnumerator            bool  moveNext   e MoveNext            while  moveNext                        sb Append e Current               moveNext   e MoveNext                if  moveNext                   sb Append                         return sb ToString              https   github com dotnet BenchmarkDotNet was used

User · Answer

FYI  the  NET 4 0 version of string Join   has some extra overloads  that work with IEnumerable instead of just arrays  including one that can deal with any type T   public static string Join string separator  IEnumerable lt string gt  values  public static string Join lt T gt  string separator  IEnumerable lt T gt  values

User · Answer

The easiest way I can see to do this is using the LINQ Aggregate method   string commaSeparatedList   input Aggregate  a  x    gt  a          x

User · Answer

Here s another extension method       public static string Join this IEnumerable lt string gt  source  string separator                return string Join separator  source

User · Answer

Since I reached here while searching to join on a specific property of a list of objects  and not the ToString   of it  here s an addition to the accepted answer   var commaDelimited   string Join      students Where i   gt  i Category    studentCategory                                    Select i   gt  i FirstName

User · Answer

We have a utility function  something like this   public static string Join lt T gt   string delimiter       IEnumerable lt T gt  collection  Func lt T  string gt  convert         return string Join  delimiter           collection Select  convert   ToArray          Which can be used for joining lots of collections easily   int   ids    1  1  2  3  5  8  13  21  34  55  89  144  233    string csv   StringUtility Join      ids  i   gt  i ToString        Note that we have the collection param before the lambda because intellisense then picks up the collection type   If you already have an enumeration of strings all you need to do is the ToArray   string csv   string Join       myStrings ToArray

User · Answer

I think that the cleanest way to create a comma-separated list of string values is simply   string Join lt string gt       stringEnumerable     Here is a full example   IEnumerable lt string gt  stringEnumerable  new List lt string gt     stringList Add  Comma    stringList Add  Separated     string Join lt string gt       stringEnumerable     There is no need to make a helper function  this is built into  NET 4 0 and above

User · Answer

I came over this discussion while searching for a good C  method to join strings like it is done with the MySql method CONCAT WS    This method differs from the string Join   method in that it does not add the separator sign if strings are NULL or empty       CONCAT WS      tbl Lastname tbl Firstname     will return only Lastname if firstname is empty  whilst      string Join       strLastname  strFirstname     will return strLastname        in the same case    Wanting the first behavior  I wrote the following methods       public static string JoinStringsIfNotNullOrEmpty string strSeparator  string strA  string strB  string strC                     return JoinStringsIfNotNullOrEmpty strSeparator  new    strA  strB  strC               public static string JoinStringsIfNotNullOrEmpty string strSeparator  string   arrayStrings                if  strSeparator    null              strSeparator               if  arrayStrings    null              return             string strRetVal   arrayStrings Where str   gt   string IsNullOrEmpty str   Aggregate      current  str    gt  current    str   strSeparator            int trimEndStartIndex   strRetVal Length - strSeparator Length          if  trimEndStartIndex gt 0              strRetVal   strRetVal Remove trimEndStartIndex           return strRetVal

User · Answer

To create a comma separated list from an IList lt string gt  or IEnumerable lt string gt   besides using string Join   you can use the StringBuilder AppendJoin method  new StringBuilder   AppendJoin  quot    quot   itemList  ToString     or   quot  new StringBuilder   AppendJoin  quot    quot   itemList   quot

User · Answer

you can convert the IList to an array using ToArray and then run a string join command on the array    Dim strs As New List Of String  Dim arr As Array arr   strs ToArray

User · Answer

You could also use something like the following after you have it converted to an array using one of the of methods listed by others   using System  using System Collections Generic  using System Linq  using System Text  using System IO  using System Net  using System Configuration   namespace ConsoleApplication       class Program               static void Main string   args                        CommaDelimitedStringCollection commaStr   new CommaDelimitedStringCollection                string   itemList      Test1    Test2    Test3                 commaStr AddRange itemList               Console WriteLine commaStr ToString       Outputs Test1 Test2 Test3             Console ReadLine                        Edit  Here is another example

User · Answer

I wrote a few extension methods to do it in a way that s efficient       public static string JoinWithDelimiter this IEnumerable lt String gt  that  string delim            var sb   new StringBuilder            foreach  var s in that                sb AppendToList s delim                      return sb ToString            This depends on       public static string AppendToList this String s  string item  string delim            if  s Length    0                return item                     return s delim item

[c#] Creating a comma separated list from IList<string> or IEnumerable<string>

Examples related to c#

Examples related to string