Hello world

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Goal

Write and run your first Go program. After this page you will have confirmed the toolchain works on your machine and you'll know the shape of every Go source file.

Prerequisites

• Go installed

The shape of a Go file

Every runnable Go program has three pieces in this order:

1. A package main line — the package this file belongs to. main is the special name for an executable.
2. import block — the standard library and third-party packages this file uses.
3. A func main() — the entry point. The program starts here and exits when it returns.

fmt is the standard library's text formatter. fmt.Println writes a line to standard output.

Code

Create a folder for this tier, then a file called main.go:

package main

import "fmt"

func main() {
	fmt.Println("hello, Mei")
}

Run it:

go run main.go

Output:

hello, Mei

go run compiles the file to a temporary binary, runs it, and discards the binary. For a permanent build, use go build.

Next → Types and variables