1. Enumerated data type & typedef

2. Enumerated Data Type An enumeration consists of a set of named integer constants. An enumeration type declaration gives the name of the (optional) enumeration tag and defines the set of named integer identifiers (called the "enumeration set," "enumerator constants," "enumerators," or "members"). A variable with enumeration type stores one of the values of the enumeration set defined by that type. Variables of enum type can be used in indexing expressions and as operands of all arithmetic and relational operators. Enumerations provide an alternative to the #define preprocessor directive with the advantages that the values can be generated for you and obey normal scoping rules.

3. Enumerated Data Type enum identifier { enumerator-list } Example #include void main() { clrscr(); enum month { jan = 1, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec }; enum month this_month; this_month = feb; printf("%d",this_month); getch(); }

4. typedef A typedef declaration lets you define your own identifiers that can be used in place of type specifiers such as int, float, and double. A typedef declaration does not reserve storage. The names you define using typedef are not new data types, but synonyms for the data types or combinations of data types they represent. The name space for a typedef name is the same as other identifiers. The exception to this rule is if the typedef name specifies a variably modified type. In this case, it has block scope. typedef int LENGTH; LENGTH length, width, height;