Chapter 13: Functions in C

Definition: A named block of code that performs a specific action. Executed when called by its name.

Benefits:

• Reusability: Write once, use multiple times.
• Modularity: Divides complex programs into smaller, manageable parts.
• Easier Maintenance: Debugging and modifying specific functions is easier than a monolithic program.

• Built-in Functions: Part of the C language library (e.g., printf(), scanf()). Ready-made and optimized.
• User-defined Functions: Created by the programmer to perform specific tasks.

Function Head/Header: First line of definition. Contains Return-type, Name, and Parameters.

Function Body: Block of code inside curly braces {}.

Function Declaration (Prototype): Model of the function, usually written before main(). Ends with a semicolon. Syntax: return_type name(parameters);

• Actual Parameters: Values passed to the function during a function call.
• Formal Parameters: Variables defined in the function header to receive values.

• Local Variables: Declared inside a function. Scope is limited to that function. Created when function starts, destroyed when it ends (automatic lifetime).
• Global Variables: Declared outside all functions. Scope is the entire program. Created at program start, destroyed at program termination.