DEV Community

Karen Payne
Karen Payne

Posted on

C# Different way to join string array

Learn how to create a comma delimited string that goes past using String.Join method.

Code blocks

Rather than use separate methods, all code is presented in the main method of a Console project.

{ code }
Enter fullscreen mode Exit fullscreen mode

Where code is isolated from all other code.

Note, index = 1; in this case is out of scope from the assignment.

{ { int index = 0; } index = 1; }
Enter fullscreen mode Exit fullscreen mode

Convention method to join

Using String.Join to create a comma delimited string of month names which once joined as a string there is no easy method to modify data e.g. add/remove, in this case a month name.

Console.WriteLine(string.Join(",", DateTimeFormatInfo.CurrentInfo.MonthNames[..^1]));
Enter fullscreen mode Exit fullscreen mode

CommaDelimitedStringCollection

CommaDelimitedStringCollection class provides methods and properties to add, edit, test if values exists, iterate with a for statement and much more.

🛑 Downside and one may guess as the name implies, the delimiter can not be changed from a comma.

Create an instance of CommaDelimitedStringCollection and add month names.

CommaDelimitedStringCollection result = new(); result.AddRange(DateTimeFormatInfo.CurrentInfo.MonthNames[..^1]);
Enter fullscreen mode Exit fullscreen mode

Display the results

Console.WriteLine($"\t{result}");
Enter fullscreen mode Exit fullscreen mode

Remove the current month.

var currentMonthName = DateTime.Now.ToString("MMMM", CultureInfo.InvariantCulture); result.Remove(currentMonthName);
Enter fullscreen mode Exit fullscreen mode

Insert the current month back in.

result.Insert(DateTime.Now.Month -1, currentMonthName);
Enter fullscreen mode Exit fullscreen mode

What is cool is iterating the collection, in this case month name.

for (var index = 0; index < result.Count; index++) { Console.WriteLine($"{index +1, -3}{result[index]}"); }
Enter fullscreen mode Exit fullscreen mode

Results

1 January 2 February 3 March 4 April 5 May 6 June 7 July 8 August 9 September 10 October 11 November 12 December
Enter fullscreen mode Exit fullscreen mode

Useful for debugging

Example, a developer is testing the following method to find files.

static class FileHelpers { /// <summary> /// Find files with no regard to if the user has permissions /// </summary> /// <param name="path">Folder name to check</param> /// <param name="extensions">file extensions</param> /// <returns></returns> public static string[] FilterFiles(string path, params string[] extensions) => extensions .Select(filter => $"*.{filter}") .SelectMany(item => Directory.EnumerateFiles( path, item, SearchOption.AllDirectories)).ToArray(); }
Enter fullscreen mode Exit fullscreen mode

Rather than using StringBuilder the developer can use CommaDelimitedStringCollection.

{ AnsiConsole.MarkupLine("[yellow]Files found[/]"); CommaDelimitedStringCollection result = new(); var files = FileHelpers.FilterFiles(Path.Combine(AppDomain.CurrentDomain.BaseDirectory),"txt","json"); foreach (var file in files) { result.Add(Path.GetFileName(file)); } Console.WriteLine($"\t{result}"); Console.WriteLine(result.Contains("appsettings.json").ToYesNo()); }
Enter fullscreen mode Exit fullscreen mode

Using numerics

As the name implies CommaDelimited*StringCollection* there are no overloads for other types but we can simply do a conversion.

For int array, use the following language extension.

static class Extensions { /// <summary> /// int array to string array /// </summary> /// <param name="sender"></param> public static string[] ToStringArray(this int[] sender) => sender.Select(x => x.ToString()).ToArray(); }
Enter fullscreen mode Exit fullscreen mode

Usage

int[] items = { 1, 2, 3 }; CommaDelimitedStringCollection result = new(); result.AddRange(items.ToStringArray());
Enter fullscreen mode Exit fullscreen mode

Check if 3 is in the collection.

result.Contains("3")
Enter fullscreen mode Exit fullscreen mode

Set to read only

For when the collection should not be modified, use SetReadOnly() method.

{ AnsiConsole.MarkupLine("[yellow]Files found[/]"); CommaDelimitedStringCollection result = new(); var files = FileHelpers.FilterFiles(Path.Combine(AppDomain.CurrentDomain.BaseDirectory), "txt", "json"); foreach (var file in files) { result.Add(Path.GetFileName(file)); } Console.WriteLine($"\t{result}"); Console.WriteLine(result.Contains("appsettings.json").ToYesNo()); result.SetReadOnly(); try { result.Add("SomeFile.txt"); } catch (Exception e) { Console.WriteLine(e); } }
Enter fullscreen mode Exit fullscreen mode

Rather than try/catch

result.SetReadOnly(); if (!result.IsReadOnly) { result.Add("SomeFile.txt"); }
Enter fullscreen mode Exit fullscreen mode

screenshot of code samples

Clear the collection

See the Clear method.

Clone the collection

See the Clone method

NuGet packages required

🔸 System.Configuration.ConfigurationManager

Source code

Can be found here which is in a GitHub repository with a mix of other code samples.

Top comments (0)