Variable Definition in C

Variable Definition in C

A variable definition tells the compiler where and how much storage to create for
the variable. A variable definition specifies a data type and contains a list of one
or more variables of that type as follows:

type variable_list;

6. VARIABLES
Here, type must be a valid C data type including char, w_char, int, float, double,
bool, or any user-defined object; and variable_list may consist of one or more
identifier names separated by commas. Some valid declarations are shown here:

int                   i, j, k; char                c, ch; float                f, salary; double            d;

The line int i, j, k; declares and defines the variables i, j and k; which instruct
the compiler to create variables named i, j, and k of type int.
Variables can be initialized (assigned an initial value) in their declaration. The
initializer consists of an equal sign followed by a constant expression as follows:

type variable_name = value;

Some examples are:

extern             int d = 3, f = 5; // declaration of d and f. int                   d = 3, f = 5; // definition and initializing d and f. byte                z = 22; // definition and initializes z. char                x = 'x'; // the variable x has the value 'x'.

For definition without an initializer: variables with static storage duration are
implicitly initialized with NULL (all bytes have the value 0); the initial value of all
other variables are undefined.