C Programming Functions

Name: C Programming Functions
Author: Mike McMillan

Understand how to write value-returning and void functions in C programs

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Hi, this is Mike McMillan, and in this lesson, I'm going to demonstrate some uses of functions that are already built in to see before we launch into our own discussion of how to create user defined functions. So, I'm gonna look at a couple of functions from the math world and from the string world just to give you an idea of what functions are and really to kind of talk about how functions work and why we need them. First, let's look at a math function, and we looked at these a little bit before. We'll do the first one. Now, what I'm gonna do is print out results. So, this first example is the square root function. The square root function takes a number as its argument and returns the square root of that number. So, let's talk a little bit about definitions. Many functions take arguments, in other words, which is the data that we pass into a function to perform some task. So, square root always takes the numbers, since that's what we're trying to compute the square root of. Arguments to functions are always enclosed in parentheses. Those parentheses are actually called the function call operator. So, parentheses are actually an operator. You can't manipulate that in C, but in C++, you can actually define your own function call operations, but for now, just to understand that function arguments have to be placed inside parenthesis, and then the result of square root nine will be the return value. The function like square root is called a value-returning function, and that value, the value that it computes, the square root is what gets returned from the function back to the calling program. So, that's going to be stored right here. I could also put it in a variable just like that. So, we talk about value-returning functions having a value that it returns and an argument that is passed into it, and some functions have more than one argument. So, when we run this program, we should see three as the result, 3.0, as a result of what we saw in the printf statement, and then, of course, that will also be the value that's stored in the variable sq. Another example is absolute value. So, again, absolute value is a mathematical argument that takes a number and returns that number's absolute value. So, in this case, the value that's gonna be stored in the variable abval is one, because the absolute value of negative one is one, and, again, that's an example of a value-returning function. On the string side, we have a function called strlen, or most people call that string length. Strlen, or stringlen, takes a string as it's argument and returns the number of characters in that string. So, we'll count one, two, three, four, five, six, seven, eight, nine, 10, 11, 12. I count 13. Let's comment out our code from earlier, and run that, and there's our 13. So, that's another example of a value-returning function. Now let's look at one more function that's value-returning. And again, to save time, I'm not gonna print this out, because that's not the point. The point, I just wanna show you an example of a different function that has two arguments this time. Strcat, or string concatenate, takes a string as its first argument, and concatenates the second argument to it, to give us one string that consists of the original string and then the added string. That's another example of a value-returning function. So, that wraps up this video on some function examples to try to get you some insight and some familiarity with how functions work. In my next video, we're gonna get into actually creating our own user-defined value-returning functions. These are functions that will take an argument and return a value from the function.

Beginner Provider : Mike McMillan 5 Lessons · 30m in Arabic, German, English, Spanish, French, Portuguese, Chinese

Course Description

One of the most important programming techniques is the ability to effectively use functions. In this course on Functions, you’ll learn how to modularize your code so that each important task can be defined separately and then the different functions can be used together to form a complete program.

In these lessons, you’ll learn how a value-returning function takes data and transforms it in some way, such as converting a temperature from Celsius to Fahrenheit. You’ll also learn how void functions are used to execute a function without returning a value, like when you want to display a greeting in several different places in a program. We’ll explain how to create each type of function and where to incorporate them into your programs. We’ll also cover how functions make program code easier to read, and also easier to debug by isolating errors to a specific function within all that code.

What You'll Learn

Modularize code by defining each important task as a separate function
Create value-returning functions that take data and transform it, such as converting Celsius to Fahrenheit
Create void functions that execute without returning a value, such as displaying a greeting in several places
Build functions with multiple parameters and apply built-in functions
Apply variable scope when working with functions
Use functions to make program code easier to read and easier to debug by isolating errors

Key Takeaways

Effectively using functions is one of the most important programming techniques, allowing code to be modularized so each task is defined separately and combined into a complete program.
A value-returning function takes data and transforms it in some way, such as converting a temperature from Celsius to Fahrenheit.
A void function executes without returning a value, such as displaying a greeting in several different places in a program.
Functions make program code easier to read and easier to debug by isolating errors to a specific function.
The course covers how to create each type of function and where to incorporate them into programs.

Frequently Asked Questions

What will I learn in this C Programming Functions course?

You will learn how to create code using advanced C functions, how to modularize your code so each task can be defined separately, and the difference between value-returning functions and void functions.

What is the difference between value-returning functions and void functions?

A value-returning function takes data and transforms it in some way, such as converting a temperature from Celsius to Fahrenheit, while a void function executes without returning a value, such as displaying a greeting in several different places in a program.

What topics or lessons does this course cover?

The course covers Built-In Functions, Value Returning Functions, Void Functions, Functions with Multiple Parameters, and Functions and Variable Scope.

How can functions help with debugging?

Functions make program code easier to read and also easier to debug by isolating errors to a specific function within the code.