https://highon.coffee/blog/penetration-testing-tools-cheat-sheet/#nmap-udp-scanning
Print Format
package main
import "fmt"
func main() {
fmt.Print("hello world")
}
Print line format
package main
import "fmt"
func main() {
fmt.println("hello world")
}
Print Format view - represent Printf
package main
import "fmt"
func main() {
fmt.Printf("there are %v apples\n", 3)
var x = "John"
var y = 36
fmt.Printf("name is %v, age is %#v\n", x, y)
}
Print - it return a string instead of printing.
package main
import "fmt"
func main() {
var x = "gino"
var y = 36
var s = fmt.Sprintf("name is %v, age is %v\n", x, y)
fmt.Println(s == "name is gino, age is 36\n") // true
}
Print - it return a string instead of printing.
package main
import "fmt"
func main() {
var x = "gino"
var y = 36
var s = fmt.Sprintf("name is %v, age is %v\n", x, y)
fmt.Println(s == "name is jino, age is 36\n") // false
}
Printf format values and types
package main
import "fmt"
func main() {
//v represent for value
//T represent by Type
var x = 3
fmt.Printf("%v\n", x) // 3
fmt.Printf("%T\n", x) // int
var x2 = 3.4
fmt.Printf("%v\n", x2) // 3.4
fmt.Printf("%T\n", x2) // float64
}
Comment golang
package main
import "fmt"
func main() {
// this is a comment - single line
fmt.Println(3)
/* -> multiline
this is a block comment
can contain multiple lines
cannot be nested
*/
}
Intepreted String Literal
package main
import "fmt"
func main() {
var x = "ABC and ♥"
fmt.Println(x)
// abc and ♥
}
Literal newline is not allowed
package main
import "fmt"
func main() {
var x = "ABC \"XYZ\" ♥"
fmt.Println(x)
// abc and ♥
}
If you don't want backslash to have special meaning, use `
package main
import "fmt"
var x = `long text
many lines
tab too`
func main() {
fmt.Printf("%v\n", x)
fmt.Printf("%T\n", x)
}
String Index
package main
import "fmt"
func main() {
var x = "abc"
fmt.Printf("%#v\n", x[0]) // 0x61
fmt.Printf("%#v\n", x[1]) // 0x62
fmt.Printf("%#v\n", x[2]) // 0x63
}
String Length - len(string) → returns the number of bytes in string.
package main
import "fmt"
func main() {
var x = "welcome"
fmt.Printf("%v\n", len(x))
fmt.Printf("%T\n", len(x))
}
Sub-string s[n:m] → returns a substring of s from index n to m (excluding m). The return value's type is string.
package main
import "fmt"
func main() {
var x = "012345"
fmt.Printf("%#v\n", x[2:3]) // "2"
fmt.Printf("%#v\n", x[2:4]) // "23"
fmt.Printf("%#v\n", x[2:2]) // ""
}
Join String - Use + to join string
package main
import "fmt"
func main() {
fmt.Printf("%v\n", "a"+"b") // ab
}
Embed Expression in String?
package main
import "fmt"
func main() {
var name = "John"
var age = 30
var x = fmt.Sprintf("Name: %v, Age: %v", name, age)
fmt.Println(x) // Name: John, Age: 30
}
import strings function
package main
import (
"fmt"
"strings"
)
var print = fmt.Println
func main() {
print(strings.ToUpper("jino")) //uppercase
print(strings.ToLower("WELCOME TO ALL")) //lowercase
print("ab" == "ab") // 0
print(strings.Contains("abcd", "bc")) // true
print(strings.HasPrefix("abca", "ab")) // true
print(strings.HasSuffix("abca", "ca")) // true
print(strings.ToLower("ABC") == "abc") // true
print(strings.Trim(" abc ", " ") == "abc") // true
print(strings.Count("abcaab", "ab") == 2) // true
print(strings.Index("abc", "bc") == 1) // true
print(strings.Join([]string{"a", "and", "b"}, " ") == "a and b") // true
// sprintit into slice
print(strings.Split("a b c", " ")) // [a b c]
}
Variable with Value
package main
import "fmt"
func main() {
var x = 3
fmt.Println(x) // 3
fmt.Printf("%T\n", x) // int
}
Variable Parallel Assignment
package main
import "fmt"
func main() {
var x, y = 3, 4
fmt.Println(x, y) // 3 4
}
Variable Scope
Variables in a package are local to the package. Variables inside function are local to the function.
package main
import "fmt"
// package level variable
var x = 3
func main() {
// function level variable
var y = 4
fmt.Println(x, y) // 3 4
}
Variable Syntax Shortcut Inside Function
package main
import "fmt"
func main() {
k := 3 // var k = 3
fmt.Println(k)
}
Grouping Variable Declaration
package main
import "fmt"
var (
a int
b = 2
c = "some"
d int
)
func main() {
fmt.Println(a, b, c, d) // 0 2 some 0
}
Constant variable - Constants are declared like variables, but its value cannot be changed.
package main
import "fmt"
func main() {
const c1 = 345
const c2 = true
var c3 = "JINO"
fmt.Println(c1, c2, c3) // 345 true
}
IF Statement
package main
import "fmt"
func main() {
var x = 3
if x > 0 {
fmt.Println("yes")
}
}
IF ELSE Statement
package main
import "fmt"
func main() {
var x = 3
if x < 0 {
fmt.Println("yes")
} else {
fmt.Println("NO)
}
}
ELSE IF Statement
package main
import "fmt"
func main() {
var x = 3
if x < 0 {
fmt.Println(-1)
} else if x > 0 {
fmt.Println(1)
} else {
fmt.Println(0)
}
}
IF ELSE statement - Shortform
package main
import "fmt"
func main() {
var x = 3
// if statement can start with a short statement
if i := -2; x < i {
fmt.Println("no")
}
fmt.Println("yes")
}
Example program
import (
"fmt"
"os"
"os/exec"
)
func main() {
if len(os.Args) == 2 {
var x = os.Args[1]
var cmd = exec.Command(x)
output, err := cmd.Output()
if err != nil {
panic(err)
}
fmt.Println(string(output))
} else {
fmt.Println("your input is not valid")
os.Exit(1)
}
fmt.Println("programming end")
}
example one:
package main
import "fmt"
func main(){
var num[100] int
var temp,sum,avg int
fmt.Print("Enter number of elements: ")
fmt.Scanln(&temp)
for i := 0; i < temp; i++ {
fmt.Print("Enter the number : ")
fmt.Scanln(&num[i])
sum += num[i]
}
avg = sum/temp
fmt.Printf("The Average of entered %d number(s) is %d",temp,avg)
}
package main
import "fmt"
type person struct {
firstname string
lastname string
contactInfo
}
type contactInfo struct {
zipcode int
mail string
}
func main() {
jim := person{
firstname: "j",
lastname: "jinojoe",
contactInfo: contactInfo{
mail: "[email protected]",
zipcode: 89898,
},
}
jimPointer := &jim
jimPointer.updateName("newname")
jim.print()
}
func (p person) print() {
fmt.Printf("%+v", p)
}
func (pointerToPerson *person) updateName(newname string) {
(*pointerToPerson).firstname = newname
}
package main
import "fmt"
type person struct {
firstname string
lastname string
contactInfo
}
type contactInfo struct {
zipcode int
mail string
}
func main() {
jim := person{
firstname: "j",
lastname: "jinojoe",
contactInfo: contactInfo{
mail: "[email protected]",
zipcode: 89898,
},
}
jimPointer := &jim
jimPointer.updateName("newname", "secondNewname", "newMailid", 623402)
jim.print()
}
func (p person) print() {
fmt.Println(p)
}
func (pointerToPerson *person) updateName(newname string, secondNewName string, newMail string, newZipcode int) {
(*pointerToPerson).firstname = newname
(*pointerToPerson).lastname = secondNewName
(*pointerToPerson).contactInfo.mail = newMail
(*pointerToPerson).contactInfo.zipcode = newZipcode
}
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