Enumeration Types & Storage Class

Published on: Mon Apr 05 2010

Enumeration Types

Int Float and double have a large range.
Chars are stored using their Interger ASCII values 0 to 255. This only takes up one int byte.
Data type specifies a range of values
A variable of a specified type can have any value form this range or set.
What if values are from a set of non numeric values? IE Days in the week
Enumeration means to describe or list or name the values, one by one.
Used to name a finite set

enum color {red,blue,green,yellow}

color is the tag name “enum color” is the type You can give variables this type, and assign them values from the set you described

enum color c1,c2; c1 = green

That just declared two variables of type enum color. Say you get bored of typing on enum color all the time. You can define the type using typedef.

typedef int newIntType

That just created a new type of interger variable type called newIntType. Enum stores things as intergers. For example, in the color example, red corresponds to 0, blue to 1 and so on…

enum day{sun,mon,tues,wednes,thurs,fri,sat}; typedef enum day days; days today = fri; switch (today) { case fri: //And so on…. }

Enums are good for switch cases! Storage class Variables have two attributes, type and storage class. Storage class in how and where memory is allocated. There are four types in C. auto(matic), extern, register, static. Auto – Used for local variables, kept on the stack Extern – global variables, present until the program stops running, not kept in Stack. Register – defaults to auto if necessary, kept on the processor chip. Very special and used to improve execution speed, treated as advice only.