Structures

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Summary

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• What is a structure?

• How to define a structure

• Structure instances

What is a structure?

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In C-like programming languages, a structure is a user-defined data type that can be used to group items of possibly different types into a single type. The variables defined inside a structure can only be accessed in this structure or from an instance.

How to define a structure

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In Shard, structures are defined using the struct keyword. The name is placed right after it, and then you can define the body, which contains all the structure fields. A field is an item inside a structure.

For example, let’s define a structure to represent a point in a 2D space:

struct Point {
    var x: i32;
    var y: i32;
    var name: i8;
}

The structure contains a variable field named x of type i32 which represents the X position of the point, another variable field named y of type i32 which represents the Y position of the point, and a last field named name of type i8, used to store a single character which represents the name of the point.

Defining a structure will create a new type which has the name of this structure.

Structure instances

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You can now create instances of your structures, using the new types defined because of your structures.

var p: Point;       // create an instance of Point

The fields of the structure can be acessed using ..

var px: i32 = p.x;
var py: i32 = p.y;
var pname: i8 =  p.name;

Here is an example of a function that moves a point to a new position:

func move_point(var p: *Point, var new_x: i32, var new_y: i32) {
    p[0].x = new_x;
    p[0].y = new_y;
}