Validate Float Logic?

I spent the evening trying to figure a good way to validate user input of a floating point number from a string . The following code snippet works, but seems complicated to me. I am sure there is probably a more efficient way. If so could someone please give me some constructive criticism or pointers.

Code:

---

////////////////////////////////////
// Validate floating point number.//
////////////////////////////////////

int Decimal = 0;

for (int i = 0; i < nLen; i++ )
{
if ( !isdigit(pbuffer[i]))
{
                if ( Decimal == 0 )
                {
                        if( pbuffer[i] == '.' )
                        {
                                Decimal = 1;
                                continue;
                        }
                }
                MessageBox (NULL, TEXT ("Enter a floating point number."),
                        TEXT ("Invalid input!"), MB_ICONINFORMATION) ;
                return TRUE;        // break out of switch statement.
}
}

// pbuffer is valid so do calculations.

---

http://www.dinkumware.com/manuals/re...ib.html#strtod

This might help.

EDIT: The link only works sometimes. Once you get in there, look up strtod if it doesn't automatically bring you to it.

Thanks for the info. I'll try it out.