Working with Functions in C

by Zachary Bennett

Functions are a core component of the C programming language . This course will teach you everything you need to know about functions in C including user-defined functions and functions that are available within the C standard library.

What you'll learn

Without a proper understanding of functions, a software developer is limited in terms of their ability to create modular systems that are easy to reason about and maintain.

In this course, Working with Functions in C, you will learn how to use functions in order to create programs and applications in C that are easy to test and easy to maintain:

  1. learn what functions are in C and why they are so important
  2. explore how to create your own user-defined functions in order to create modular, reusable code that is easy to maintain and test
  3. take a deep-dive into the C standard library functions that are available
By the end of this course, you will have a deep understanding of both user-defined and standard library functions in C.

Course FAQ

What will you learn in this C programming language course?

In this course, you will learn about function anatomy, function declarations and prototypes, value and reference passing, and C standard library functions/marcros.

Are there any prerequisites for this course?

Before taking this course, you should be familiar with the basics of the C syntax and programming fundamentals.

What are user-defined functions?

A user-defined function is a single comprehensive unit that contains a block of code to perform a specific task.

What are C standard library functions?

The C standard library functions include macros, type definitions and functions for tasks such as string handling, mathematical computations, input/output processing, memory management, and other operating system services.

What are the benefits of C functions?

Some benefits of C functions are: avoiding the repitition of code, increasing program readability, reducing the chance of erros, and easier modification.

About the author

Zach is currently a Lead Software Developer at OpalSoft where he uses tools such as Scala, TypeScript, Python, Docker, Node, and Angular. Zach has a passion for GIS programming along with open-source software. You can view some of his work on GitHub ( and Stack Overflow (

Ready to upskill? Get started