C Macros Tutorial

1. Defining a Simple Macro

A macro is defined using the #define preprocessor directive. Here's an example of a simple macro definition:

#define PI 3.14159

This defines PI as a constant value of 3.14159, and every occurrence of PI in the code will be replaced by this value before compilation.

2. Macros with Parameters

Macros can also accept parameters, similar to functions, allowing more complex replacements:

#define SQUARE(x) ((x) * (x))

In this case, SQUARE(x) will compute the square of a number passed to it. For example, SQUARE(5) would be replaced with 25.

3. Advantages of Macros

Macros provide several advantages, such as:

• Improved readability by replacing magic numbers with meaningful names.
• Increased efficiency through code reusability.
• Faster execution as macros are expanded at compile-time.

4. Macros vs Functions

While macros can sometimes replace functions, they have key differences:

• Macros are expanded at compile-time, whereas functions are executed at runtime.
• Macros do not perform type checking, which can sometimes lead to errors.
• Macros are more efficient for simple expressions but may cause code duplication if overused.

5. Conclusion

Macros are a useful tool in C for defining constants and code snippets that need to be reused multiple times. Understanding how to properly use macros can help optimize your code and improve its readability.