Best Practices for Writing Go Code: A Beginner’s Guide

package main

import "fmt"

func main() {
    // Using var keyword
    var age int
    age = 25

    // Short variable declaration
    name := "John"

    fmt.Printf("Name: %s, Age: %d\n", name, age)
}

package main

import "fmt"

// Function with parameters and return value
func add(a int, b int) int {
    return a + b
}

func main() {
    result := add(3, 5)
    fmt.Println("Result:", result)
}

package main

import "fmt"

func main() {
    // If statement
    num := 10
    if num > 5 {
        fmt.Println("Number is greater than 5")
    }

    // For loop
    for i := 0; i < 5; i++ {
        fmt.Println(i)
    }

    // Switch statement
    day := "Monday"
    switch day {
    case "Monday":
        fmt.Println("It's Monday")
    default:
        fmt.Println("It's another day")
    }
}

// main.go
package main

import (
    "fmt"
    "github.com/user/module"
)

func main() {
    result := module.SomeFunction()
    fmt.Println(result)
}

package main

import (
    "fmt"
    "os"
)

func main() {
    file, err := os.Open("nonexistent.txt")
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    defer file.Close()
    fmt.Println("File opened successfully")
}

// This is a single-line comment
/*
This is a multi-line comment
It can span multiple lines
*/

// main.go
package main

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

// main_test.go
package main

import "testing"

func TestAdd(t *testing.T) {
    result := Add(2, 3)
    if result != 5 {
        t.Errorf("Add(2, 3) = %d; want 5", result)
    }
}

// Bad naming
func a(b, c int) int {
    return b + c
}

// Good naming
func addNumbers(num1, num2 int) int {
    return num1 + num2
}

// Bad: Function with multiple responsibilities
func processDataAndPrintResult(data []int) {
    sum := 0
    for _, num := range data {
        sum += num
    }
    fmt.Println("Sum:", sum)
}

// Good: Separate functions
func calculateSum(data []int) int {
    sum := 0
    for _, num := range data {
        sum += num
    }
    return sum
}

func printSum(sum int) {
    fmt.Println("Sum:", sum)
}

package main

import "fmt"

// Shape interface
type Shape interface {
    Area() float64
}

// Rectangle struct
type Rectangle struct {
    Width  float64
    Height float64
}

// Implement the Area method for Rectangle
func (r Rectangle) Area() float64 {
    return r.Width * r.Height
}

func printArea(s Shape) {
    fmt.Println("Area:", s.Area())
}

func main() {
    rect := Rectangle{Width: 5, Height: 10}
    printArea(rect)
}