private Token NextInteger(char ch)
{
string value = ch.ToString();
int ich;
for (ich = this.NextChar(); ich != -1 && char.IsDigit((char)ich); ich = this.NextChar())
value += (char)ich;
if (ich != -1 && (char)ich == '.')
return this.NextReal(value);
this.PushChar(ich);
return new Token(value, TokenType.Integer);
}