This cheatsheet gives you a quick reference to Go’s syntax, tools, and best practices. Keep it handy while coding.

Basics

Hello World:

package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}

Variables:

var name string = "Alice"
age := 30 // shorthand, type inferred

Constants:

const Pi = 3.14

Functions:

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

Data Types

• string, int, float64, bool
• Arrays: [3]int{1, 2, 3}
• Slices: []int{1, 2, 3}
• Maps: map[string]int{"Alice": 30}
• Structs:

type Person struct {
    Name string
    Age  int
}

Control Structures

If/Else:

if x > 0 {
    fmt.Println("Positive")
} else {
    fmt.Println("Non-positive")
}

Switch:

switch day {
case "Monday":
    fmt.Println("Start of week")
default:
    fmt.Println("Other day")
}

For loops:

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

Pointers

x := 10
p := &x
fmt.Println(*p) // dereference

Concurrency

Goroutines:

go func() {
    fmt.Println("Hello from a goroutine")
}()

Channels:

ch := make(chan int)
go func() { ch <- 42 }()
fmt.Println(<-ch)

Error Handling

data, err := os.ReadFile("file.txt")
if err != nil {
    log.Fatal(err)
}

Testing

Create example_test.go:

package main

import "testing"

func TestAdd(t *testing.T) {
    if add(2, 3) != 5 {
        t.Error("Expected 5")
    }
}

Run tests:

go test

Tooling Commands

• go run file.go — Run a program
• go build — Compile to binary
• go test — Run tests
• go fmt — Format code
• go get — Fetch dependencies
• go mod init <module> — Create a module

Best Practices

• Keep functions short and focused
• Use gofmt to ensure consistent style
• Handle errors explicitly
• Prefer composition over inheritance
• Keep your main package minimal

Final Thoughts

Go’s simplicity makes it easy to remember the basics, but this cheatsheet is a great quick refresher when you need it.