Baisc goLang For Hacking

A quick guide for the people who know scripting in general but don’t know goLang.

Prequests:

• Familiar with programming in general
• Familiarization with C and Python helps but not necessary
  
  

Data Types	Description
var x <type>	Variable declaration
x := <value>	Variable declaration & Assignment
var x[<size>] <type>	Array declaration
x := [3]int{0,1,2}	Array declaration & Assignment
x := []int{}	Slice of int type, flexible
x := make(map[string]int)	Maps declaration; key-value pairs
x[“a”] = 1337	Maps Assignment
nil	Zero value for pointers, interfaces, maps, slices, func types
float64 / float32	float for respective architecture

Functions	Description
fmt.Println()	Like print() in python
fmt.Printf()	Like printf() in C
fmt.Scan()	Like scanf() in C
string()	Converts int, bytes into string
append(array, value)	Append value & return new array
len(array)	Return Array length
delete(x, “key”)	Delete key:value from map “x”
errors.New(“error!”)	User-defined error

Formatting	Description
%v	Variable
%T	type of variable
%d	decimal

Example

x := 1337
fmt.Printf("%d %v %T", x, x, x)

Visibility	Scope	Snippet
Block level	inside blocks {}	x := 10
Package level	Outside all functions	var int x = 10
Global level	Outside all functions with Capital letter convention	var X int = 1337

---

Loops

For Loop

for i := 0; i<5; i++ {
	fmt.Println(i)
}

While like loop

i := 0
for i<len(array) {
	fmt.Println(i)
	i++
}

foreach like loop

for i, v := range array {
	fmt.Println("index:",i,"value:",v)
}

---

Functions

Function syntax

func sum(x int, y int) int{
	return x + y
}

Function with multiple return values

func sum_and_product(x int, y int) (int, int)
	return x+y, x*y
}

---

Struct Type

• Collection of fields

type person struct {
	name string
	age int
}

func main() {
	p := person{name:"Malcom", age:18}
}

---

Pointers

func main() {
	i := 0
	inc(&i)
}
func inc(i *int) {
	*i++
}

---

Handling Web Requests

Packages

• net/http
• io

Functions	Description
http.Get()	Returns *http.Response pointer & error
io.ReadAll(res.Body)	Returns bytes & error
defer res.Body.Close()	Close connection after function ends

Snippet

import (
	"fmt""io"
	"net/http")

func main() {
	res, err := http.Get("https://www.google.com/")
	
	checkError(err)
	defer res.Body.Close()
	
	dataBytes, err := io.ReadAll(res.Body)	
	checkError(err)
	
	content := string(dataBytes)
	fmt.Println(content)
}

// Check for errors
func checkError(err error) {
	if err != nil {
		panic(err)
	}
}

< post under construction />

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