Add separator to string at every N characters?

Question

I have a string which contains binary digits. How to separate string after each 8 digit?

Suppose the string is:

string x = \"111111110000000011111111         


        

Answer 1

This is much faster without copying array (this version inserts space every 3 digits but you can adjust it to your needs)

public string GetString(double valueField)
{
    char[] ins = valueField.ToString().ToCharArray();
    int length = ins.Length + (ins.Length / 3);
    if (ins.Length % 3 == 0)
    {
        length--;
    }
    char[] outs = new char[length];

    int i = length - 1;
    int j = ins.Length - 1;
    int k = 0;
    do
    {
        if (k == 3)
        {
            outs[i--] = ' ';
            k = 0;
        }
        else
        {
            outs[i--] = ins[j--];
            k++;
        }           
    }
    while (i >= 0);

    return new string(outs);
}

Answer 2

Regex.Replace(myString, ".{8}", "$0,");

If you want an array of eight-character strings, then the following is probably easier:

Regex.Split(myString, "(?<=^(.{8})+)");

which will split the string only at points where a multiple of eight characters precede it.

Answer 3

For every 1 character, you could do this one-liner:

string.Join(".", "1234".ToArray()) //result: 1.2.3.4

Answer 4

...or old school:

public static List<string> splitter(string in, out string csv)
{
     if (in.length % 8 != 0) throw new ArgumentException("in");
     var lst = new List<string>(in/8);

     for (int i=0; i < in.length / 8; i++) lst.Add(in.Substring(i*8,8));

     csv = string.Join(",", lst); //This we want in input order (I believe)
     lst.Reverse(); //As we want list in reverse order (I believe)

     return lst;
}

Answer 5

There's another Regex approach:

var str = "111111110000000011111111000000001111111100000000";
# for .NET 4
var res = String.Join(",",Regex.Matches(str, @"\d{8}").Cast<Match>());

# for .NET 3.5
var res = String.Join(",", Regex.Matches(str, @"\d{8}")
            .OfType<Match>()
            .Select(m => m.Value).ToArray());

Answer 6

Try this:

var s = "111111110000000011111111000000001111111100000000";
var list = Enumerable
    .Range(0, s.Length/8)
    .Select(i => s.Substring(i*8, 8));
var res = string.Join(",", list);