The set of characters that may appear 'C' program is called the character set for 'c'.These include some graphic as well as non-graphic characters.The 'C' character set consists of upper case and lower case alphabets,special character,digits and white spaces.The alphabet and digits together are called the alphanumeric character.
'C' is case sensitive language, it means lower and upper case are different.
. Special character
, Comma..by net