Go — Packages

Package declaration

// math/utils.go
package utils

func Add(a, b int) int {
    return a + b
}

func Multiply(a, b int) int {
    return a * b
}

Importing packages

package main

import (
    "fmt"
    "myproject/math"
)

func main() {
    fmt.Println(math.Add(3, 4))
}

Package init

package utils

func init() {
    fmt.Println("Package initialized")
}

Internal packages

myproject/
├── internal/
│   └── auth/
│       └── auth.go
├── cmd/
│   └── main.go
└── go.mod

Mini Practice

Write Go code that:

1. Creates a package with exported functions
2. Imports and uses the package
3. Uses package init function
4. Organizes code with internal packages

Up Next

In the next lesson, you'll learn about Modules — dependency management.