string strInput = "1100100100001111110110101010001000100001011010001100001000110100";
int len1 = strInput.Length;
string final = "";
for (int i = 0; i < strInput.Length; i++)
{
char c = strInput[i];
if (char.IsDigit(c))
final += strInput[i].ToString();
}
int len2 = final.Length;
The very first char before '1100....' is an Unicode which is non printable char whose unicode value is 8237
Unicode Decimal Code &#8237;[
^]