Removing extra commas from string after using String.Join to convert array to string (C#)

Question

I'm converting an array into a string using String.Join . A small issue I have is that, in the array some index positions will be blank. An example is below:

array[1] = "Firstcolumn"
array[3] = "Thirdcolumn"

By using String.Join(",", array);, I'll get the following:

Firstcolumn,,Thirdcolumn

Note the extra ,.

How can I remove the extra commas from the string, or ideally not include blank indices when using String.Join?

Answer 1

Try this :):

var res = string.Join(",", array.Where(s => !string.IsNullOrEmpty(s)));

This will join only the strings which is not null or "" .

Answer 2

A simple solution would be to use linq, by filtering out the empty items before joining.

// .net 3.5
string.Join(",", array.Where(item => !string.IsNullOrEmpty(item)).ToArray());

In .NET 4.0 you could also make use of string.IsNullOrWhiteSpace if you also want to filter out the items that are blank or consist of white space characters only (note that in .NET 4.0 you don't have to call ToArray in this case):

// .net 4.0
string.Join(",", array.Where(item => !string.IsNullOrWhiteSpace(item)));

Answer 3

您可以使用linq删除空字段。

var joinedString = String.Join(",", array.Where(c => !string.IsNullOrEmpty(c));

Answer 4

Extension method:

public static string ToStringWithoutExtraCommas(this object[] array)
{
    StringBuilder sb = new StringBuilder();
    foreach (object o in array)
    {

        if ((o is string && !string.IsNullOrEmpty((string)o)) || o != null)
            sb.Append(o.ToString()).Append(",");
    }

    sb.Remove(sb.Length - 1, 1);

    return sb.ToString();
}

Answer 5

正则表达方案：

yourString = new Regex(@"[,]{2,}").Replace(yourString, @",");

Answer 6

String.Join(",", array.Where(w => !string.IsNullOrEmpty(w));

Answer 7

string.Join(",", string.Join(",", array).Split({","}, StringSplitOptions.RemoveEmptyEntries));

V（ '_'）V

Answer 8

Simple extension method

namespace System
{
    public static class Extenders
    {
        public static string Join(this string separator, bool removeNullsAndWhiteSpaces, params string[] args)
        {
            return removeNullsAndWhiteSpaces ? string.Join(separator, args?.Where(s => !string.IsNullOrWhiteSpace(s))) : string.Join(separator, args);
        }
        public static string Join(this string separator, bool removeNullsAndWhiteSpaces, IEnumerable<string> args)
        {
            return removeNullsAndWhiteSpaces ? string.Join(separator, args?.Where(s => !string.IsNullOrWhiteSpace(s))) : string.Join(separator, args);
        }
    }
}

Usage:

var str = ".".Join(true, "a", "b", "", "c");
//or 
var arr = new[] { "a", "b", "", "c" };
str = ".".Join(true, arr);

Answer 9

string.Join(",", Array.FindAll(array, a => !String.IsNullOrEmpty(a)));

How about this one? Cons and pros comparing to LINQ solution? At least it shorter.