C# adding a character in a string

Question

I know I can append to a string but I want to be able to add a specific character after every 5 characters within the string

from this string alpha = abcdefghijklmnopqrstuvwxyz

to this string alpha = abcde-fghij-klmno-pqrst-uvwxy-z

Answer 1

Remember a string is immutable so you will need to create a new string.

Strings are IEnumerable so you should be able to run a for loop over it

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string alpha = "abcdefghijklmnopqrstuvwxyz";
            var builder = new StringBuilder();
            int count = 0;
            foreach (var c in alpha)
            {
                builder.Append(c);
                if ((++count % 5) == 0)
                {
                    builder.Append('-');
                }
            }
            Console.WriteLine("Before: {0}", alpha);
            alpha = builder.ToString();
            Console.WriteLine("After: {0}", alpha);
        }
    }
}

Produces this:

Before: abcdefghijklmnopqrstuvwxyz
After: abcde-fghij-klmno-pqrst-uvwxy-z