Programming Concepts | CompTIA Tech+ FC0-U71 | 4.3

In this post, we’ll cover some fundamental ideas that are essential to programming:  identifiers, including variables and constants; arrays; functions; and objects, which encompass properties, attributes, and methods.

Understanding these core concepts will give you a strong foundation as you prepare for the exam.  Let’s dive into the details.

Identifiers:  Variables & Constants

Let’s begin with identifiers.

An identifier is essentially the name we give to different elements in our programs.  Identifiers can represent variables, constants, functions, or other programming entities.  They help us track and manipulate data within a program.

Variables

A variable is a storage location in programming that holds data which can be changed or modified during program execution.

• Purpose:  The purpose of variables is to store temporary data that a program may need to refer to and manipulate as it runs.
• Example:  If you were creating a program to calculate the area of a rectangle, you would use variables to store the values for the rectangle’s length and width.

In this example, length, width, and area are all variables.  The values stored in length, and width can change, and the program can calculate a new area each time.

• Naming Variables:  In most programming languages, variables must follow certain rules:
  • They should start with a letter (or underscore in some languages).
  • They cannot contain spaces or special characters.
  • They should be descriptive so the purpose of the variable is clear.

Constants

A constant, as the name suggests, is a value that does not change during the execution of the program.  Once it’s set, it remains the same.

• Purpose:  Constants are used when you need to store data that shouldn’t be altered.  For example, mathematical values like Pi or fixed configuration settings should be constraints.
• Example

In this example, PI is a constant, because the value of PI doesn’t change.  By using a constant, you prevent accidental changes to important data and improve code readability.

Many programming languages, such as Python and JavaScript, don’t have built-in support for constants, but developers use conventions like all-uppercase letters (e.g., PI) to signify that a variable should not change.

Arrays

Next, let’s talk about arrays.

An array is a data structure that allows you to store multiple values in a single variable.  These values are usually of the same data type, such as integers or strings, and they are stored in contiguous memory locations.  Arrays make it easier to handle multiple pieces of data efficiently.

• Purpose:  Arrays are used when you need to store collections of data, such as a list of numbers, a set of names, or any series of related items.  Instead of creating individual variables for each item, you can use one array to store them all.
• Example

In this example, the array fruits contains four elements.  You can access individual items in the array by referencing their index, like this:

The array index starts at 0, so fruits [0] returns “apple”, and fruits [1] returns “banana”, and so on.

• Arrays in Action:  Arrays are especially useful in loops.  You can iterate through an array to perform operations on each element:

In this case, the program will print each fruit in the list one by one.

Functions

Now, let’s move on to functions.

A function is a block of organized, reusable code that performs a single, well-defined task.  Functions are a key building block in programming, and they help make code modular and easier to manage.

• Purpose:  Functions allow us to group related lines of code into a single entity, making our code more readable, reusable, and maintainable.  Functions can take input data, perform operations on it, and return a result.
• Example

In this example, we define a function called calculate_area ( ) that takes two inputs, length and width, and returns the product of the two values.  You can then call this function wherever you need to calculate an area:

• Benefits of Functions
  • Code Reusability:  Once a function is defined, it can be called any number of times without needing to rewrite the code.
  • Modularity:  Breaking a program into small, manageable functions improves the organization and clarity of the code.
  • Maintenance:  If you need to make changes to how something works, you only need to update the function,  and every place that calls the function will automatically use the updated code.
• Function Parameters:  Functions can accept parameters, which allow you to pass data into them when you call them.  In the example above, length and width are parameters.
• Return Values:  Functions can return values, providing the result of their operations to the calling code.

Objects:  Properties, Attributes, & Methods

Finally, let’s talk about objects.  This concept is central to Object-Oriented Programming (OOP), which is a common paradigm in programming.

An object is a collection of data and methods that operate on that data.  Objects are instances of classes, which define the structure and behavior of the objects.  In simpler terms, classes act as blueprints, and objects are the actual things you create from those blueprints.

• Purpose:  Objects allow programmers to model real-world entities and organize code in a way that’s easier to manage, especially in large programs.

Properties and Attributes

Properties or attributes are the data stored within an object.  They represent the characteristics or traits of the object.

• Example:  If we had an object representing a car, the car’s properties could include its color, make, model and year.

Here, make, model, color, and year are attributes of the car class.  When you create an object from this class, you can assign these attributes values:

The object my_car now has properties that describe the specific car.

Methods

Methods are functions defined inside a class that describes the behaviors or actions an object can perform.

• Purpose:  Methods allow objects to perform actions, often using or modifying the object’s properties.  Just like regular functions, methods can accept parameters and return values.
• Example

Here, start_engine ( ) is a method that belongs to the Car class.  It uses the object’s properties to display a message.  You can tell this method on the my_car object:

By using methods, we can define the actions our objects can take.  Each object created from a class has access to the methods defined in that class.

Bringing It all Together

To wrap things up, let’s summarize the key programming concepts we’ve covered:

• Identifiers:  These are names used for variables, constants, functions, and objects in programs.
  • Variables store data that can change, while constants hold fixed values.
• Arrays:  Arrays are data structures used to store collections of related data, accessed by index.
• Functions:  Functions are blocks of reusable code that perform specific tasks.  They improve modularity and reusability in programs.
• Objects:  Objects are instances of classes that contain properties (attributes) and methods (functions) that allow them to perform actions.

Understanding these core concepts is essential for programming and helps make code efficient, organized, and easy to maintain.  These concepts are foundational for the CompTIA Tech+ exam and will aid in your preparation.