Golang Cheat Sheet
Golang Cheat Sheet 1. Basic Syntax Comments // Single-line comment /* Multi-line comment */ Variables and Data Types var x int = 5 y := 10 // Type inference // Basic types var ( a bool = true b int = 10 c float64 = 3.14 d string = "Hello" ) Constants const Pi = 3.14 const ( StatusOK = 200 StatusNotFound = 404 ) Operators // Arithmetic: +, -, *, /, %, ++, -- // Comparison: ==, !=, <, >, <=, >= // Logical: &&, ||, ! // Bitwise: &, |, ^, <<, >> Type Casting i := 42 f := float64(i) s := string(i) 2. Control Structures Conditional Statements if x > 0 { // code } else if x < 0 { // code } else { // code } switch day { case "monday": // code case "tuesday", "wednesday": // code default: // code } Loops for i := 0; i < 10; i++ { // code } for condition { // while loop equivalent } for { // infinite loop } for index, value := range collection { // range loop } Break and Continue Statements for { if condition { break } if otherCondition { continue } } 3. Functions Function Declaration and Definition func greet(name string) string { return "Hello, " + name } Parameters and Return Values func divide(a, b float64) (float64, error) { if b == 0 { return 0, errors.New("division by zero") } return a / b, nil } Anonymous Functions / Lambdas func() { fmt.Println("Anonymous function") }() add := func(a, b int) int { return a + b } Scope and Closures func adder() func(int) int { sum := 0 return func(x int) int { sum += x return sum } } 4. Data Structures Arrays/Slices var arr [5]int slice := []int{1, 2, 3, 4, 5} slice = append(slice, 6) Maps m := make(map[string]int) m["key"] = 42 value, exists := m["key"] Sets // Go doesn't have a built-in set type // Use a map[Type]bool instead set := make(map[string]bool) set["item"] = true 5. Object-Oriented Programming Structs and Methods type Rectangle struct { width, height float64 } func (r Rectangle) Area() float64 { return r.width * r.height } Interfaces type Shape interface { Area() float64 } 6. Error Handling if err != nil { log.Fatal(err) } // Custom errors type MyError struct { message string } func (e *MyError) Error() string { return e.message } 7. File I/O // Reading data, err := ioutil.ReadFile("file.txt") // Writing err := ioutil.WriteFile("file.txt", data, 0644) // Working with directories files, err := ioutil.ReadDir(".") 8. Modules and Packages import ( "fmt" "math" ) // Creating modules // In go.mod file: // module example.com/mymodule 9. Standard Library fmt: Formatted I/O os: Operating system functionality io: Basic I/O interfaces net/http: HTTP client and server implementations encoding/json: JSON encoding and decoding time: Time and duration functions 10. Concurrency // Goroutines go function() // Channels ch := make(chan int) ch <- 42 // Send value := <-ch // Receive // Select select { case msg1 := <-ch1: // Use msg1 case msg2 := <-ch2: // Use msg2 default: // Run if no channel is ready } 11. Memory Management Go uses automatic garbage collection defer keyword for cleanup operations 12. Important Language-Specific Features Goroutines and Channels Defer statements Panic and Recover go generate 13. Best Practices and Style Guide Use gofmt for standard formatting Follow naming conventions (camelCase for unexported, PascalCase for exported) Prefer composition over inheritance Handle errors explicitly 14. Useful Resources Official Documentation: https://golang.org/doc/ Go by Example: https://gobyexample.com/ Go Playground: https://play.golang.org/ Popular packages: gin-gonic/gin, spf13/cobra, gorm.io/gorm