Use symbolic names for
constants 
In general all numeric constants should be defined
symbolic names either through C's preprocessor's #define or with a const
definition. 
Put digits on both sides of a
floating point value 
Floating point literals should include digits on both
sides of the decimal point.

Hexadecimal constants should
use capitals "A" through "F" and small "x" 
Hexadecimal numbers should always have the
"x" in lowercase and the letters "A" through "F" in
uppercase. This will promote the hexadecimal literal number to look more like a constant
instead of a variable. Another good rule of thumb is to always make a hexadecimal number
an even number of characters.
Bad 
0Xace 
0xbad0 
Good 
0x0ACE 
0xBAD0 

Long word constants should
use capital "L" suffix 
Long int numbers should be followed by an uppercase
"L" since a lowercase "l" could be confused with the number one
("1").
