We’ve just learned the importance of structs in grouping complex data types. But how do we define the structs we’ll use in our programs? In this exercise, we will introduce the syntax for defining structs.

The definition of a struct includes its name and its fields. A field is one of the internal variables inside a struct. We use the following template:

// Struct names begin with a capital letter in Go
type NameOfStruct struct {
  // Struct fields go here
}

Let’s say we want to define a 2D point with an x and y coordinate. We could define two variables x and y and use them throughout our program. However, using multiple related variables in this way is error-prone. We might use x when we mean y, and dealing with many points could cause confusion.

A better way to represent a 2D point is to create a struct called Point which contains both coordinates. Defining Point in this way logically groups together the relevant data types. We would define the struct for Point like so:

type Point struct {
  x int
  y int
}

Using this new type, we would be able to pass Point information around our program as a single variable!

Now that have our struct defined, we need to be able to use them. In the next exercise will learn to create instances of our defined structs. First, let’s practice defining them in our programs.