A floating_ point constant is a sequence of one or more digits,
followed by a period, ``
.
'',
followed by one or more digits.
Thus,
2.0
is legal, and
2.
and
.5
are illegal.
It may be followed by an exponent.
An exponent consists of one of the characters ``
e
'',
``
E
'', ``
f
'', ``
F
'' followed by a signed or unsigned
integer.
The value of a floating_ point constant
is determined as is usual with scientific notation.
As with integers, it is unsigned.
Hence, for example,
0.2
,
2.0e - 1
,
20.0e - 2
are all equivalent.