Lesson 1: Go Basics¶

Big Picture¶

flowchart TD
    A["Go source file (.go)"] --> B["package declaration"]
    B --> C["import statements"]
    C --> D["func main() — program entry point"]
    D --> E["fmt.Println → stdout"]

Every executable Go program follows this skeleton: declare the package, import what you need, and put your logic in main().

Printing¶

• fmt.Println() — print with newline
• fmt.Print() — print without newline
• fmt.Printf() — formatted printing

Go Naming and Access Conventions¶

Go uses the first letter of a name to control whether other packages can access it:

• Capitalized names are exported: Println, NewServer, and User can be accessed from another package.
• Lowercase names are package-private: main, calculateTotal, and user can only be accessed from within the same package.
• Capitalize a function, type, variable, constant, method, or struct field only when it is part of the package's public API.

• Prefer lowercase names for implementation details that callers do not need.

• Use a dot to access an exported identifier from an imported package:

  • Here, fmt is the package name and Println is an exported function. main stays lowercase because the Go runtime looks for that exact special function name; it is not called from another package.

• The same export rule applies to struct fields:

  package profile
  
  type User struct {
      Name     string // accessible as user.Name from another package
      password string // accessible only inside package profile
  }
  

Common naming conventions:

• Use camelCase for unexported names and PascalCase for exported names; do not use underscores.
• Keep package names short, lowercase, and singular, such as http, json, or profile.
• Avoid repeating the package name: prefer http.Server over http.HTTPServer.
• Acronyms normally keep consistent capitalization: userID, UserID, HTTPClient, and ServeHTTP.
• Use short names like i in small scopes, but descriptive names like customerCount in larger scopes.

Code Walkthrough¶

//Every Go file starts with `package main` (for executable programs)
package main

import "fmt" //Import Statement

func main() {
    fmt.Println("Hello, Go!")       // newline
    fmt.Print("no newline ")
    fmt.Printf("formatted: %d\n", 42)

    name := "world"
    fmt.Printf("Hello, %s\n", name)
}

Check Your Understanding¶