floating constant

hey everyone .. i am trying to write a regular expression for the floating constant...here's the definition of floating constant:

A floating constant consists of an integer part, a decimal point, a fraction part, an e or E, an optionally signed integer exponent and an optional type suffix, one of f, F, l or L. The integer and fraction parts both consist of a sequence of digits. Either the integer part or the fraction part (not both) may be missing; either the decimal point or the e and the exponent (not both) may be missing.

what i am trying to do is write an expresstion for it similar to this one which was done for natural numbers:

Natural numbers (integers > 0) can be represented
using:
non zero digit ! 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
digit ! 0 | non zero digit
natural number ! non zero digit digit *

hii all
can any one post the answer of the above question???
thanks in advance

why not 3 regular expressions?
1: check if its integer
2: if its a float
3: if its of the form 12.323e+3

those should be simple