2009-06-12 From list to delimited string

2009-06-12 from-list-to-delimited-string

# Title: From list to delimited string
# Author: Mikael Lundin
# Link: http://blog.mikaellundin.name/2009/06/12/from-list-to-delimited-string.html

EnumerableExtensions.cs

public static class EnumerableExtensions
{
    public static string ToDelimitedString<T>(this IEnumerable<T> list, string separator)
    {
        return ToDelimitedString(list, separator, DefaultConverter);
    }

    public static string ToDelimitedString<T>(this IEnumerable<T> list, string separator, Converter<T, string> converter)
    {
        // List can't be null  
        if (list == null)
        {
            throw new ArgumentNullException("list", "Tried to create a string from a list that was null");
        }

        if (separator == null)
        {
            throw new ArgumentNullException("separator", "Must specify a separator even if it is string.Empty");
        }
        Contract.EndContractBlock();

        // If converter was null, we probably wanted default converter  
        if (converter == null)
        {
            return list.ToDelimitedString(separator, DefaultConverter);
        }

        // Start the process of creating the string  
        var sb = new StringBuilder();
        foreach (var o in list)
        {
            sb.Append(converter(o));
            sb.Append(separator);
        }

        /* Remove last seperator (if there is one) */
        if (sb.Length > 0)
        {
            sb.Length -= separator.Length;
        }

        return sb.ToString();
    }

    private static string DefaultConverter<T>(T item)
    {
        return item.ToString();
    }
}

Example.cs

public static void Main(string[] args)
{
    // Simple example
    string[] names = { "Joe", "Jack", "James" };
    names.ToDelimitedString(",");

    // A bit more complex
    var books = new Book[]
                    {
                        new Book { Isbn = 1590598504, Title = "Expert F#", Price = 614},
                        new Book { Isbn = 735619670, Title = "Code Complete", Price = 324},
                    };
    books.ToDelimitedString("\n", book => string.Format("ISBN={0}, Title={1}, Price={2:c}", book.Isbn, book.Title, book.Price));
}