Hello, World!
Make the computer say hello, every programmer's first program.
1package main
2
3import "fmt"
4
5func main() {
6 fmt.Println("Hello, world!")
7}
$ go run main.go
Hello, world!
Every line, explained
package main- Every Go file starts by saying which package it belongs to. package main means "this is a program you can run", and Go will look inside it for func main.
import "fmt"- import brings in a package from Go's standard library. "fmt" (short for format) is the one full of printing tools, like fmt.Println.
func main() {- func main() { ... } is where a Go program starts. When you run the program, Go finds func main inside package main and runs everything between its braces, top to bottom.
fmt.Println("Hello, world!")- fmt.Println(...) prints what is inside the brackets to the terminal, then moves to a new line (Println is short for "print line"). The capital P matters: in Go, the tools a package shares all start with a capital letter. The text goes inside double quotes: in Go, strings ALWAYS use double quotes.
}- This closing brace } ends func main.