Lesson 8: Variable Declaration and Initialization

Declaration

Declaring a variable tells the compiler three things:

1. The name of the variable.
2. The type of data it will store.
3. The amount of memory to reserve.

Syntax: data_type variable_name;

c int age; double salary; char initial;

Initialization

Initialization is the process of assigning an initial value to a variable.

Syntax: data_type variable_name = value;

c int count = 0; double price = 19.99; char status = 'R';

You can declare multiple variables of the same type in one statement: c int x, y, z = 50;

Local vs. Global Variables (Preview)

• Local Variables: Declared inside a function. They are not initialized automatically and contain garbage values until explicitly assigned.
• Global Variables: Declared outside all functions. They are automatically initialized to zero (0 for numeric types, NULL for pointers).

Best Practice: Always initialize local variables to prevent unpredictable behavior caused by garbage data.