Go programming provides another data type called interfaces which represents a set of method signatures. The struct data type implements these interfaces to have method definitions for the method signature of the interfaces.
Syntax
/* define an interface */
type interface_name interface {
method_name1 [return_type]
method_name2 [return_type]
method_name3 [return_type]
...
method_namen [return_type]
}
/* define a struct */
type struct_name struct {
/* variables */
}
/* implement interface methods*/
func (struct_name_variable struct_name) method_name1() [return_type] {
/* method implementation */
}
...
func (struct_name_variable struct_name) method_namen() [return_type] {
/* method implementation */
}
Example
package main
import (
"fmt"
"math"
)
/* define an interface */
type Shape interface {
area() float64
}
/* define a circle */
type Circle struct {
x,y,radius float64
}
/* define a rectangle */
type Rectangle struct {
width, height float64
}
/* define a method for circle (implementation of Shape.area())*/
func(circle Circle) area() float64 {
return math.Pi * circle.radius * circle.radius
}
/* define a method for rectangle (implementation of Shape.area())*/
func(rect Rectangle) area() float64 {
return rect.width * rect.height
}
/* define a method for shape */
func getArea(shape Shape) float64 {
return shape.area()
}
func main() {
circle := Circle{x:0,y:0,radius:5}
rectangle := Rectangle {width:10, height:5}
fmt.Printf("Circle area: %f\n",getArea(circle))
fmt.Printf("Rectangle area: %f\n",getArea(rectangle))
}
When the above code is compiled and executed, it produces the following result −
Circle area: 78.539816
Rectangle area: 50.000000
