C#: Sort characters in a string

Last update on June 24 2025 12:57:14 (UTC/GMT +8 hours)

Sort Characters in String

Write a C# Sharp program to sort characters in a given string (uppercase/lowercase letters and numbers). Return the newly sorted string.

Sample Data:
("AAAbfed231") -> "AAAbdef123"
(" ") -> "Blank string!"
("Python") -> "hnoPty"
("W3resource") -> "ceeorrsuW3"

Sample Solution:

C# Sharp Code:

using System;
using System.Linq;

namespace exercises
{
    class Program
    {
        static void Main(string[] args)
        {
            // Initialize and process different input strings
            string text = "AAAbfed231";
            Console.WriteLine("Original string: " + text);
            Console.WriteLine("Sorted string: " + test(text));

            text = " ";
            Console.WriteLine("Original string: " + text);
            Console.WriteLine("Sorted string: " + test(text));

            text = "Python";
            Console.WriteLine("Original string: " + text);
            Console.WriteLine("Sorted string: " + test(text));

            text = "W3resource";
            Console.WriteLine("Original string: " + text);
            Console.WriteLine("Sorted string: " + test(text));
        }

        // Method to sort and concatenate characters and digits in a string
        public static string test(string text)
        {
            // Check if the input string is null, empty, or consists only of whitespace characters
            bool flag = string.IsNullOrWhiteSpace(text);

            // If the string is blank, return "Blank string!"
            if (flag)
                return "Blank string!";

            // Extract digits and sort them in ascending order
            var text_nums = text.Where(char.IsDigit).OrderBy(el => el).ToList();

            // Extract letters, convert them to lowercase, sort them alphabetically, then by descending original character order
            var text_chars = text.Where(char.IsLetter)
                .Select(el => new { l_char = char.ToLower(el), _char = el })
                .OrderBy(el => el.l_char)
                .ThenByDescending(el => el._char)
                .ToList();

            // Concatenate the sorted characters and digits and return the resulting string
            return new string(text_chars.Select(el => el._char).Concat(text_nums).ToArray());
        }
    }
}

Sample Output:

Original string: AAAbfed231
Sorted string: AAAbdef123
Original string:  
Sorted string: Blank string!
Original string: Python
Sorted string: hnoPty
Original string: W3resource
Sorted string: ceeorrsuW3

For more Practice: Solve these Related Problems:

Write a C# program to sort characters in a string in case-insensitive order followed by numeric sort.
Write a C# program to sort characters in reverse order but keep the digits in ascending order.
Write a C# program to group digits, uppercase, and lowercase letters, then sort within each group.
Write a C# program to sort only alphabetic characters in a string and keep other characters in place.

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