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

Ugly but less garbage:

private string InsertStrings(string s, int insertEvery, char insert)
{
    char[] ins = s.ToCharArray();
    int length = s.Length + (s.Length / insertEvery);
    if (ins.Length % insertEvery == 0)
    {
        length--;
    }
    var outs = new char[length];
    long di = 0;
    long si = 0;
    while (si < s.Length - insertEvery)
    {
        Array.Copy(ins, si, outs, di, insertEvery);
        si += insertEvery;
        di += insertEvery;
        outs[di] = insert;
        di ++;
    }
    Array.Copy(ins, si, outs, di, ins.Length - si);
    return new string(outs);
}

String overload:

private string InsertStrings(string s, int insertEvery, string insert)
{
    char[] ins = s.ToCharArray();
    char[] inserts = insert.ToCharArray();
    int insertLength = inserts.Length;
    int length = s.Length + (s.Length / insertEvery) * insert.Length;
    if (ins.Length % insertEvery == 0)
    {
        length -= insert.Length;
    }
    var outs = new char[length];
    long di = 0;
    long si = 0;
    while (si < s.Length - insertEvery)
    {
        Array.Copy(ins, si, outs, di, insertEvery);
        si += insertEvery;
        di += insertEvery;
        Array.Copy(inserts, 0, outs, di, insertLength);
        di += insertLength;
    }
    Array.Copy(ins, si, outs, di, ins.Length - si);
    return new string(outs);
}