Introduction to Functions

A function is a self-contained block of code created to execute a specific task. It serves as a reusable component, streamlining development by promoting cleaner, modular, and more efficient code. Think of it as a small program within your main application, designed to handle a particular operation. It is called from within a section of code. When the function’s code has been executed, the control returns to the calling code.

Function as an opaque box

Think of a function as an opaque box designed to perform a specific task without needing to understand what is happening under the hood. This box is given a name, it receives certain inputs (arguments or parameters), and based on these inputs, it produces a corresponding result (output). Once a function is defined, it can be called (or invoked) from other parts of the program, using its name, as many times as needed. For example, let’s say you have a function called CircleArea. This function calculates the area of a circle. It takes as input the radius of the circle and, after performing the required operations, outputs the calculated area of the circle. We can use this function repeatedly with different radii to get the area of various circles without needing to understand the specific formula used within the function.

Benefits of a function

A function offers several benefits. Some of these are written below:

• Reusability: A function allows us to write code only once and reuse it as many times as we want, thus reducing the lines of code.

• Modularity: A function allows us to divide complex code into smaller, more manageable problems. If we have a big, complex problem, we can divide this problem into several parts and thus create a function to tackle each of these problems.

• Maintainability and readability: Code written in a function is more meaningful and simple than the whole code, potentially thousands of lines, written in the main function. As the code is divided into pieces, it is also easier to understand, manage, and update. If we want to change functionality, we only need to change the code in that certain function, and everything else will remain the same.

Syntax

The general form of a function is: