awesome-cheatsheets/languages/golang.md

Golang

Summary

• Introduction
  • Hello World
  • Go CLI Commands
  • Go Modules
• Syntax
  • Basic Types
  • Variables

Hello World

package main 

import "fmt"

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

Go CLI Commands

# Compile & Run code
$ go run [file.go]

# Compile
$ go build [file.go]
# Running compiled file
$ ./hello 

# Test packages
$ go test [folder]

# Install packages/modules
$ go install [package]

# List installed packages/modules
$ go list

# Update packages/modules
$ go fix

# Format package sources
$ go fmt

# See package documentation
$ go doc [package]

# Add dependencies and install
$ go get [module]

# See Go environment variables
$ go env

# See version
$ go version

Go Modules

• Go projects are called modules
• Each module has multiple packages
• Each package should has a scoped functionality. Packages talk to each other to compose the code
• A module needs at least one package, the main
• The package main needs a entry function called main

# Create Module
$ go mod init [name] 

Tip: By convention, modules names has the follow structure:

domain.com/user/module/package

Example: github.com/spf13/cobra

Basic Types

Type	Set of Values	Values
bool	boolean	true/false
string	array of characters	needs to be inside ""
int	integers	32 or 64 bit integer
int8	8-bit integers	[ -128, 128 ]
int16	16-bit integers	[ -32768, 32767]
int32	32-bit integers	[ -2147483648, 2147483647]
int64	64-bit integers	[ -9223372036854775808, 9223372036854775807 ]
uint8	8-bit unsigned integers	[ 0, 255 ]
uint16	16-bit unsigned integers	[ 0, 65535 ]
uint32	32-bit unsigned integers	[ 0, 4294967295 ]
uint64	64-bit unsigned integers	[ 0, 18446744073709551615 ]
float32	32-bit float
float64	64-bit float
complex64	32-bit float with real and imaginary parts
complex128	64-bit float with real and imaginary parts
byte	sets of bits	alias for uint8
rune	Unicode characters	alias for int32

Variables

// Declaration
var int value 

// Initialization
value = 10

// Declaration + Initialization + Type inference
var isActive = true

// Short declaration (only inside functions)
text := "Hello"

// Multi declaration
var i, j, k = 1, 2, 3

// Variable not initialized = Zero values
// Numeric: 0
// Boolean: false
// String: ""

var number int // 0
var text string // false
var boolean bool // ""

// Type conversions
// T(v) converts v to type T

i := 1.234 // float
int(i) // 1