<aside> 💡 Modularization in C refers to the process of dividing a large program into smaller, more manageable parts called modules. Each module is a self-contained unit of code that performs a specific function or task.

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A module provides a collection of functions that share a common aspect or purpose.

There exists 3 key advantages:

• Re-usability: can be used by many clients
• Maintainability: easier to debug and maintain
• Abstraction: clients don’t need to understand how the functions are implemented

Declaration

In C, a function or variable must be declared before it can be accessed

A declaration introduces an identifier into a program and specifies a type

Declaration vs. Definition

• Declaration ⇒ It only specifies the type of an identifier
• Definition ⇒ It instructs C to create the identifier

Variable declaration

// this program demonstrates VARIABLE declarations

#include <stdio.h>
#include "cs136-trace.h"

extern int g;              // variable DECLARATION

int main(void) {
  printf("%d\\n", g);       // this is now ok
  trace_int(g);
}

int g = 7;

(Note that it uses the “extern” keyword)