var array = new string[] { "000000000000111010010101010000000000000000", 
    "111010101000111100000000000000000110010000", 
    "000010101010101010010000000000000000000000", 
    "100001010100101000000000110000000010001001", 
    "110010101010000000000000000000000000000000" };

var spa = new int[] { 0, 8, 16, 32 };

foreach (var item in array)
{
    var index = -1;
    while ((index = item.IndexOf('1', index + 1)) >= 0)
    {
        for (int i = 1; i < spa.Length; i++)
        {
            if (index < spa[i])
            {
                var r = index - spa[i - 1];
                Console.WriteLine(r);
                break;
            }
        }
    }
}