Join a string using delimiters

Question

What is the best way to join a list of strings into a combined delimited string. I\'m mainly concerned about when to stop adding the delimiter. I\'ll use C# for my example

Answer 1

This is a Working solution in C#, in Java, you can use similar for each on iterator.

        string result = string.Empty; 

        // use stringbuilder at some stage.
        foreach (string item in list)
            result += "," + item ;

        result = result.Substring(1);
        // output:  "item,item,item"

If using .NET, you might want to use extension method so that you can do list.ToString(",") For details, check out Separator Delimited ToString for Array, List, Dictionary, Generic IEnumerable

// contains extension methods, it must be a static class.
public static class ExtensionMethod
{
    // apply this extension to any generic IEnumerable object.
    public static string ToString(this IEnumerable source,
      string separator)
    {
        if (source == null)
           throw new ArgumentException("source can not be null.");

        if (string.IsNullOrEmpty(separator))
           throw new ArgumentException("separator can not be null or empty.");

        // A LINQ query to call ToString on each elements
        // and constructs a string array.
        string[] array =
         (from s in source
          select s.ToString()
          ).ToArray();

        // utilise builtin string.Join to concate elements with
        // customizable separator.
        return string.Join(separator, array);
    }
}

EDIT:For performance reasons, replace the concatenation code with string builder solution that mentioned within this thread.