Working with Go

Hola Mundo in Go

Here is your first go program.

package main
 
import "fmt"
 
func main() {
    fmt.Println("Hola Mundo!")
}

All programs must be part of a package, you use main as the package for executable programs.

You must import all packages used, including the standard library packages. In this example, the standard library fmt is used for formatted I/O.

The standard library is your best friend in Go, it is extensive, often you will not need any third-party dependencies and can rely on just features in the standard library. You can browse all available standard library packages at: http://golang.org/pkg/.

The main package requires a main() function, this is called when the program is run.

Go will run init() function before main(), if it exists.

Here is an expanded Hello World program that uses a global variable phrase defined as a string. All variables have types. The go compiler will automatically detect the type if possible.

package main
 
import "fmt"
 
var phrase string
 
func init() {
    phrase = "Hola Mundo!"
}
 
func main() {
    fmt.Println(phrase)
}

To run the program in your terminal, save to a file hello.go and run using go run:

$ go run hello.go
Hola Mundo!