Go

Introduction

From c++ by google c++ author will convert to exe
go get githublink→ to download pkg and put under folder pkg

it has main function to run go run filename.go

package main //-> our package name 
 
imort "fmt"
 
import ("fmt","math") //-> to import multiple pkg
 
func main(){
	fmt.Println("hello")
}

Data types

string, bool, int, byte , float32 ,float64, arrays
using var keyword and const → to not reassign
var name string = “d” (if directly assing vaule we don’t need to mention the data type)
var age = 23
name := “test” → this kind of declaration we can be only defined inside function
name,email := “test”,”email”

Arrays

var name [2] string 
name[0] = "1"
 
name := [2]string("1","2") //size optional
//slice 
name := [2]string{"1","2"}
 
len(name) //-> to get length
 
name[1:2] //-> slice the array

Struct

type Animal struct {
class string
age int
}
 
var teddy = Animal{ class:"bear",age:14}
or 
Animal{"bear",14}
 
//teddy.age

Map

 emails :=  make(map[string]string)
 
 := map[stringstring{"key":"value"}
 
emails["name"]= "key"

Function

function name (params type) returnType {
	cmd..
}
//type is not mandatory
 
name(params)
 
#multiple return vaule
function name (params type) (int,bool..) {
	return 4,true,..
}
 number ,bool := name()
we can also give name for the return type of function like 
 
function name () (number int , ..) -> it is purely for doc
#Error Handling

Arguments are passed as copy use pointer for call by reference

Pointers

package main
 
import "fmt"
 
func main() {
    // Declare a variable
    var num int = 10
    
    // Declare a pointer variable
    var ptr *int
    
    // Assign the address of num to ptr
    ptr = &num
    
    // Access the value through the pointer
    fmt.Println("Value of num:", num)
    fmt.Println("Value of num through pointer:", *ptr)
    
    // Modify the value through the pointer
    *ptr = 20
    fmt.Println("New value of num:", num)
}

Conditions

if x<y || cond2  {
	//code
}  else if {
	//code
} else {
	//code
}
 
//switch
color := "red"
 
switch color {
	case "red":
		//code
  case "":
			//code
	default:
		//code
}

Loops

i :=1
for i<=10 {
	//code 
  i++
}
 
for i:=1 i<10;i++ {
 //code
}
 
//using range
ids := []int{33,33}
 
for i,id := range ids {
	
}
 
//range with map
 
for k,v := range map { }

Runes

Go’s runes are used to represent single characters. ‘A’ →65 Runes are kept as numeric codes

If you declare a variable without assigning it a value, that variable will contain the zero value

short variable declaration

instead of explicitly declaring the type of the variable and later assigning to it with = , you do both at once using := .

quantity := 4

If the name of a variable, function, or type begins with a capital letter, it is considered exported and can be accessed from packages outside the current one.

Conversions

Only same type can be do math operation float and int cannot to convert

int(3.0)
float64(9)

Packages

Go tools look for package code in a special directory (folder) on your computer called the workspace. By default, the workspace is a directory named go in the current user’s home directory.

The workspace directory contains three subdirectories

bin, which holds compiled binary executable programs.
pkg, which holds compiled binary package files.
src, which holds Go source code.

others

Split your application into components written as regular Go interfaces. Don’t fuss with any networking or serialization code. Focus on your business logic. (https://serviceweaver.dev/)

Go routine → make threads simple
channel

Go

Table of Contents