Flutter and Dart Cookbook

Chapter 3. Implementing Functions

In this chapter, we will move beyond the fundamentals of Dart and introduce functions. As you may have noticed, we have already used a number of functions (e.g., main and print). In this chapter we will explore the main use cases for using functions.

Building more complex applications will certainly require developers to progress beyond simple constructs. At a minimum, an awareness of some essential concepts and algorithms is desirable. Over the course of this chapter you will learn the foundations of code isolation.

The main use case for functions is to group instructions. The chapter begins by illustrating how to define a basic function without parameters or a return value. In most situations, this is not the pattern you will want to use. However, for learning purposes it has been included. Beyond this you will be introduced to parameters and return values. At this point, hopefully it will become clearer why adding parameters and return values is so powerful and the desired pattern to follow.

Toward the end of the chapter you will see examples of other ways to use functions. You’ll discover that, as your skills grow as a developer, so will your use of functions.

3.1 Declaring Functions

Problem

You want a common group name for instructions that perform a specific task.

Solution

Declare a function to consolidate the instructions for a task. In the following example, the getCurrentDateTime function is used to print out a date/time value: