arehmandev / cheatsheet-golang-A4

:book: Advanced Golang Syntax In A4

cheatsheet-golang-a4

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See more CheatSheets from Denny: #denny-cheatsheets

Table of Contents

• cheatsheet-golang-a4
  • Syntax Sugar: From Python To Golang
  • Golang Compact Coding
  • Array/List/Slice
  • String
  • Integer/Float
  • Conversion
  • Dict/Hashmap/Map
  • Goroutines
  • Files & Folders
  • Bit Operator
  • Math
  • queue/heapq
• Code snippets
• More links

Golang CheatSheet: https://github.com/DennyZhang/cheatsheet-golang-A4

Syntax Sugar: From Python To Golang

Name	Python	Golang
sum slice	sum([1, 2, 3])	sum := 0; for i := range nums { sum += nums[i] }
Get last item	nums[-1]	nums[len(nums)-1]
For	for i in range(10):	for i := 0; i < 10; i++
Loop list	for num in [1, 2]	for num := range[]int{1, 2} { fmt.Print(num) }
Loop string	for ch in str:	for _, ch := range str { fmt.Print(ch) }
Iterator	for num in nums:	for _, num := range nums {fmt.Print(num)}
While	while isOK:	for isOK
Reverse list	nums[::-1]	Need to create your own function. Weird!
Check ch range	ord(ch) in range(ord('a'), ord('z')+1)	ch >='a' && ch <='z'
Get min	min(2, 6, 5)

Golang Compact Coding

Name	Comment
Declare variables with initializers	var ischecked, v, str = false, 2, "yes!"
One line if statement	if a >= 1 { fmt.Print("yes") }

Array/List/Slice

Name	Comment
Make a array	var a [2]string; a[0]="hello"; a[1]="world"
Create array with given values	T := [6]int{2, 3, 7, 5, 11, 13}
Create array with given values	T := []string{"a", "c", "b", "d"}
Create dynamically-sized arrays	a := make([]int, 5)
Create dynamically-sized arrays	a := make([]int, 1, 5) // 5 is capacity
Sort string array	sort.Strings(T); fmt.Print(T)
Sort int array	sort.Ints(l[:]) //in-place change
Append item	T = append(T, "e")
Append items	T = append(T, "e", "b", "c")
Remove last item	T = T[:len(T)-1]
Slices of a array	var T2 = T[1:3] // Notice: it's a reference
Copy a list	b := make([]T, len(a)); copy(b, a)

String

Package strings

Name	Comment
Format string	fmt.Sprintf("At %v, %s", e.When, e.What)
Format string	fmt.Printf("int: %d, float: %f, bool: %t\n", 123, 78.9, true)
Split string	var L = strings.Split("hi,golang", ",")
Replace string	var str2 = strings.Replace("hi,all", ",", ";", -1)
Replace string	strings.Replace("aaaa", "a", "b", 2) //bbaa
Split string by separator	strings.Split(path, " ")
Count characters	strings.Count("test", "t")
Substring	strings.Index("test", "e")
Join string	strings.Join([]string{"a","b"}, "-")
Repeat string	strings.Repeat("a", 2) // aa
Tolower	strings.ToLower("TEST")
Trim whitespace in two sides	strings.TrimSpace("\t Hello world!\n ")
Trim trailing whitespace	strings.TrimRight("\t Hello world!\n ", "\n ")

Integer/Float

Name	Comment
Int max	MaxInt32 = 1<<31 - 1 golang math
Int min	MinInt32 = -1 << 31 golang math

Conversion

Name	Comment
Convert string to int	i, _ := strconv.ParseInt("12345", 10, 64)
Convert string to int	i, err := strconv.Atoi("-42")
Convert string to float32	f, _ := strconv.ParseFloat("3.1415", 32)
Convert int to float32	0.5*float32(age)+7>= float32(age2)
Convert int to string	s := strconv.Itoa(-42)
Convert list to string	strings.Join(list, ", ")

Dict/Hashmap/Map

Name	Comment
Create dict	map[string]int{"a": 1, "b": 2}
Create dict	make(map[string]int)
Check existence	_, ok := m[k]
Delete key	delete(m, "k1")
Create a map of lists	m := make(map[string][]string)

Goroutines

Name	Comment
Basic goroutine	example_goroutine.go

Files & Folders

Name	Comment
Read/Write files	example_file.go

Bit Operator

Name	Comment
Shift left	fmt.Print(1 << 10) // 1024
Shift right	fmt.Print(1024 >> 3) // 128

Math

Name	Comment
pow(2, 3)	int(math.Pow(2, 3)) // Default is float64

queue/heapq

Name	Comment

Code snippets

• Create 2D arrays

// static
board := [][]string{
         []string{"_", "_", "_"},
         []string{"_", "_", "_"},
         []string{"_", "_", "_"},
}

// dynamic
a := make([][]uint8, dy)
for i := range a {
    a[i] = make([]uint8, dx)
}

• Logging

import "github.com/op/go-logging"
log := logging.MustGetLogger("my-app")
log.Info("Some info...")
log.Warning("Some warning...")
log.Error("Some error!")
log.Critical("Some critical!")

• struct

type Point struct {
  X, Y int
}

var (
  v1 = Point{10, 8}
  v2 = Point{X: 1}  // Y would be 0
  v3 = Point{}      // Both X and Y is 0
  p  = &Point{10, 8} // reference: type *Point
)

func main() {
  fmt.Println(p, v1, v2, v3)
}

• Goroutines & Channels

// Goroutines
go func() {
  // do something
}

// Channels
c := make(chan T [, capacity ])
c <- t // blocks on unbuffered channels until another routine receives the value

d := <-c // blocks on unbuffered channels until another routine sends the value

close(c)

More links

• A Tour Of Go
• The Go Programming Language
• https://github.com/a8m/go-lang-cheat-sheet

TODO: Need to automatically generate A4 pdf

License: Code is licensed under MIT License.