What is a Method? The Basics of Methods, Functions and Classes


**We explore the basics of methods, functions and classes in this lesson. We use simple examples to help you better understand these programming topics.**

A method is a block of code that performs a specific task. A method can be called when an event occurs or when a statement is placed in a program. Methods are different than functions because they are used to make objects do something. A function only returns a value, but a method can return values and perform actions. Some of the most common methods are included with the print(), input() and range() functions. When you call these methods, you expect them to often return something or perform some action. Other methods will be created for specific tasks by programmers using classes to create their own objects. The examples below show how these methods work in Python:

When you start learning how to code, one of the first things you learn is what a variable is. Variables are little containers that hold data. Strings can be held in variables, numbers can be held in variables, and even Booleans (true/false values) can be held in variables.

One day, when you’re writing your code, you may find yourself wishing you could take a string, do something to it and return the result as a new string. You may wish to create a method that takes a number and returns twice the value (2 * n). Or maybe you have an ArrayList of numbers and want to add them all together.

In these cases, it would be nice if we had little containers that could hold instructions for manipulating data.

This is exactly what methods are: little containers for blocks of code that manipulate data. They enable us to write lines of code once and then call on them whenever we want instead of rewriting the same lines over and over again. This not only lets us reuse code but also makes our code easier to read by giving our methods meaningful names.

A method is a block of code which only runs when it is called. You can pass data, known as parameters, into a method. Methods are used to perform certain actions, and they are also known as functions.

A method is a block of code which only runs when it is called. You can pass data, known as parameters, into a method. Parameters are variables that act as placeholders for the values that are to be input to a method when it is called. Let’s start with an example:

def my_method(number)

puts number

end

This is the simplest example of creating a method. A def (define) keyword tells Ruby that you are defining a new method and that what follows next will be the name of your method. In this case, the name of our method is my_method. The word number in parentheses is the parameter of the method; it’s a placeholder for whatever value we want to substitute in when we call the method later on. The code inside my_method just prints out whatever value is passed in as its parameter. So if I write my_method(4), I should see 4 printed out on my screen; if I write my_method(10), I should see 10 printed out

A method is a function which is part of a class. A method can be used to transform an object or get information about an object. You can think of a method as being like a command that does something to an object or asks the object something. For example, you have probably used the .sort() method that Python has for lists.

Methods are defined inside of classes and are called with the dot operator (.). The syntax for calling a method looks like this:

object_name.method_name()

The object_name before the dot is the name of the variable containing your object, and the method_name after the dot is the name of the method you want to call on that object. Inside the parentheses, you can also pass in any arguments that your method needs to do its work.

Here’s an example:

import turtle

sally = turtle.Turtle()

sally.forward(100)

In this code, we first import turtle so that we can use it in our code. Then we create sally and make her into a Turtle(). Now she can use all of Turtle’s methods using dot notation. The last line makes sally go forward 100 spaces by calling forward(100).

A method is a series of statements that perform a computation or task. A method may return a value (as in the example below, where we have method sum which returns an int) or return nothing (void). The brackets after a method name indicate that it is a method. The part between the brackets are called the parameter list, and contains any parameters of the method. These parameters are used when calling the method. For example:

public static int sum(int x, int y) {

return x + y;

}

We can call this method like so:

int answer = sum(2, 3); //answer is now 5

The above code calls sum with two parameters and sets answer to be equal to whatever sum returns. This works because sum returns an integer (the type before the name).

What is a Method?

In object-oriented programming (OOP), a method is a procedure or function associated with a class. In many ways, the methods are similar to functions in procedural programming languages. However, in OOP, encapsulation and data hiding are important concepts. Encapsulation refers to combining an object’s data and functions into a single unit. Data hiding refers to preventing direct access to an object’s data while allowing access through its methods. Methods are therefore important because they can protect the data from being misused. This makes it easier to design robust programs that can be modified over time as requirements change.

Methods also help make a program more modular and easier to read and maintain. It is easier to find the code for adding two numbers if you know it belongs in a method called add().

In Java, the method name can be any valid identifier, but it must start with a lowercase letter. By convention, mixedCase is used for method names but this is not mandatory; other common naming conventions include using uppercase letters for acronyms (such as writePDF()). A method may be either static or non-static (or instance). The syntax of declaring a method is:

accessModifier return

Like an algebraic equation, we can use a method to express the solution to a common programming problem. Unlike an algebraic equation, methods can contain multiple expressions, and we can call that method whenever we need that set of expressions to be executed.

In this exercise, you will create a method that converts Celsius temperatures to Fahrenheit temperatures. This is the formula for converting Celsius to Fahrenheit:

F = (9 / 5) * C +32

The purpose of our method is to hide the calculation so all we have to do is provide the celsius value to get the correct fahrenheit value. Let’s get started!


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