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How do we run the code in our project?

$ go run main.go

• $ go build - compiles a bunch of go source code files
• $ go run - compiles and executes one or two files
• $ go fmt - formats all code in each file in current directory
• $ go install - compiles and "installs" a package
• $ go get - downloads raw source code of someone else's package
• $ go test - runs any tests associated with the current project

package main

import "fmt"

func main() {
	fmt.Println("Hi there!")
}

What does 'package main' mean?

Declaring package <name> at the top of a file indicates which package this particular file belongs to within a project.

There are two types of packages in Go: executable and reusable

• Executable - generates a file that we can run.
• Reusable - code used as "helpers". Good place to put reusable logic.

Note: Naming the package "main" makes it an executable file.

Note: The file with the package "main" must have a function named "main"

What does 'import "fmt"'mean?

import fmt is simply importing the "format" package (included with standard Go library). using import is how you include packages into a file.

Other standard Go packages include:

• fmt
• debug
• math
• encoding
• crypto
• io

You can see a list and documentation for all packages here: https://golang.org/pkg/

What's that 'func' thing?

func is just short for function

How is the main.go file organized?

Every file in Go will have the same organization

1. Package declaration
2. Import other packages needed
3. Declare functions and tell Go to do things