Is this a deliberate exercise in making it difficult for yourself?
> I have a function that works with Integers.
OK, so start with that.
Valid integers are also valid floats, so typing in 1234 to either of them should still work.
> Is there a function to detect the decimal point? I don't know.
It seems a rather grandiose way of putting
Code:
if ( ch == '.' ) {
// yay!, decimal point
}
> I have done a search and found methods for converting a character string to double.
So storing the intermediate string one character at a time, and calling said "string to double" with the partial string isn't allowed?