Welcome to Introduction to Programming Concepts – Part Two. After watching this video, you will be able to: Describe the purpose and use of functions in programming, and describe the purpose and use of objects in programming. Next, let’s look at the fundamental concept of functions. Functions are a consequence of the modular programming software development methodology that encourages the separation of a program into multiple modular components, where each performs a specific task within a program. So, a function is essentially a piece of structured, stand-alone, and reusable code that will perform a single specific action. This enables software developers to take a substantial, complex program and divide it into smaller, more manageable, and focused pieces. Although some programming languages may refer to them as something else, such as subroutines, procedures, methods, or modules, most modern programming languages refer to them as functions. Functions take in data as an input, then process the data, and then return the result as an output. There are essentially two types of functions. Standard library functions are the built-in functions provided by the programming language. Common examples include the ‘If’, ‘Else’, ‘While ’ and ‘Print’ functions. But programming languages also allow you to write your own functions. And once you’ve written a function, you can use it over and over again. The way that the blocks of code that make up a function are identified is different across programming languages. Some use braces, some use begin and end statements, and others use indentations for example. There are a few steps to using functions. The first thing you need to do is define (or create) a function. When you define a function, you provide a function keyword, then give the function a unique name, and you provide the statements that make up the body of the function. Once a function has been defined, it then needs to be called (or invoked). When you call a function, the specified actions within the function are performed using any specified parameters. While defining and calling functions are common to all programming languages, some programming languages, such as C and C++ , also require you to declare a function. Next, let’s look at the concept of objects. Understanding what objects are is key to understanding object-oriented programming. Object-oriented programming (or OOP) is a programming methodology that is focused on objects rather than functions, which is what procedure-oriented programming is focused on. The objects themselves will contain data in the form of properties (or attributes) and code in the form of procedures (or methods). The key distinction between the two methodologies is that where procedural programming uses methods to operate on separate data structures, OOP packages them both together, so an object operates on its own data structure. Consider the real-world objects in your life such as your car, bike, TV, or your washing machine, and ask yourself the following two questions: “What states can the object be in?” and “What behaviors can the object perform?” When you think about your answers to these questions, you will find that the answers to these questions vary across the objects. More complex objects will typically have more potential states they can be in and will be able to perform more behaviors. In programming, a software object is similar to a real-world object, conceptually speaking, in that they too consist of states (or properties) and behaviors (or methods). Software objects can be anything, such as a Windows service, a user account, a database table, or a system folder. Objects store their properties in fields (referred to as variables in some programming languages), and expose their behaviors through methods (referred to as functions in some programming languages). In this video, you learned that: • A function is a piece of structured, stand-alone, and reusable code that will perform a single specific action. • The defining and calling of functions is common to all programming languages. • Object-oriented programming is a programming methodology that is focused on objects rather than functions. • Software objects consist of properties and methods.
