[TBD]Go programming language

Ubuntu installation

64 apt update

65 apt install golang-go

66 go version

root@worker212:~/golang# go version

go version go1.13.8 linux/amd64

First coding with Go

root@worker212:~/golang/exercise/Ex_Files_Go_EssT/Exercise Files/Ch01/01_01# cat welcome.go

// Print a friendly greeting

package main

import (

"fmt"

)

func main() {

fmt.Println("Welcome Gophers ☺")

}

root@worker212:~/golang/exercise/Ex_Files_Go_EssT/Exercise Files/Ch01/01_01# go run welcome.go

Welcome Gophers ☺

root@worker212:~/golang/exercise/Ex_Files_Go_EssT/Exercise Files/Ch01/01_01# ls

welcome.go

root@worker212:~/golang/exercise/Ex_Files_Go_EssT/Exercise Files/Ch01/01_01# go build welcome.go

root@worker212:~/golang/exercise/Ex_Files_Go_EssT/Exercise Files/Ch01/01_01# ls

welcome welcome.go

root@worker212:~/golang/exercise/Ex_Files_Go_EssT/Exercise Files/Ch01/01_01# ./welcome

Welcome Gophers ☺

Go packages

go get github.com/pkg/errors -> For getting non-builtin package

fmt package
1. formatted print
  1. It can print map as well
2. Errorf
3. Fprintf
strings package
1. strings.Fields
os package
1. os.Exit(0)
2. os.stdout
log
"sync"
1. var wg sync.WaitGroup
io/ioutil
1. ioutil.ReadFile(f)
crypto/md5

Language properties

No semicolon at the end of line
It uses zero based indexing for array same as C/C++
Go has garbage collector
Go string supports unicode by default
1. String in go are immutable similar to C
  1. book[4:11]
  2. book[4:]
  3. book[:4]
2. + is used to concatenate two strings
It has int , int8 , int16 , int32 , or int64
Go support untyped variable like python (use := instead of =)
Syntax of if, switch, for are similar to C/C++
1. Case in switch can be string as well unlike C/C++
2. No need of break statement at the end of case
3. Switch can be without condition. In this case, case will have condition
4. for doesn't have () for condition
Built-in functions
1. len
2. Sprintf
3. Snprintf
Built-in data structure
1. map
  1. map[string]int{} -> Map with string as key and int as value
  2. map[string]interface -> Map with string as key and any type as value
go get
1. For installing packages
has built-in checks
1. Array out of bound panic
It has built-in test
1. go test
2. test file name should have suffix _test.go
3. Test function should have prefix Test
4. It also adds profiling via option -cpuprofile

Go keywords

range
func
- Allows more than one return value
- It passes param by reference for default and so, any change in param reflects to the argument value
- Arguments can be passed as position or via key-value
nil
- similar to C NULL
defer
- Defer the action till end of function. For example, defer calling an API
- If multiple defer, it is called in reversed order
import
- To import a package. Example - fmt
package
type
- type Trade struct -> Example
struct
- type Trade struct -> Example
- It can have function defined
- Language allows nested struct -> struct within struct
Built-in Data types
- string
- int
- float64
- bool
- map
interface
- like Java interface
error
panic function
go
- For concurrency
chan
- For concurrency
var
- Can be used to define global variable
select
make
module

Useful links

https://stackoverflow.com/questions/61536104/ioutil-readfile-no-such-file-or-directory

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