Miki Tebeka tebeka

What do you think the following program will print?

https://gist.github.com/09755207f9bdfd13f71639d3e0f301cd

This program will print: 4.

When you use iota in a const group, the values of the constants will advance according to the first operation. The << operator is "left shift". It moves the bits of a number to the left, basically multiplying it by power of 2.

For example, if we have the number 5, which (on byte, which is 8 bits) is 00000101. When you write 5 << 1 all the bits are shifted one place to the left. Making it 00001010 which is 10=5*2. When you write 5 << 2 the bits are shifted two places to the left, making it 00010100 or 20=5*4.

	package main

	import "fmt"

	type Agent struct {
	Name string
	ID int
	}

	func main() {

	package main

	import "fmt"

	func main() {
	v := [...]int{2: 7}
	fmt.Println(v)
	}

	$ echo '-2**2' \| python -m ast
	Module(
	body=[
	Expr(
	value=UnaryOp(
	op=USub(),
	operand=BinOp(
	left=Constant(value=2),
	op=Pow(),
	right=Constant(value=2))))],

	type Perm struct {
	Read bool
	Write bool
	Execute bool
	}

	type FilePerm uint8

	const (
	Read FilePerm = 1 << iota
	Write
	Execute
	)

	func main() {
	fmt.Println(Execute) // execute

	fmt.Println(unsafe.Sizeof(filePerm)) // 1
	var p Perm
	fmt.Println(unsafe.Sizeof(p)) // 3

	* (expt -2 2)
	4

	>>> (-2)**2
	4

	>>> -2**2
	-4