V language summary

hello.v

// updated for v0.1.19
//import http // need to install openssl
import json

const (
	PI      = 3.14
	NUMBERS = [1, 2, 3]
)

struct Point {
	x int
	y int
}

fn (p Point) draw() string {
	return 'Point${p.str()}' // uses str()
}
fn (p Point) str() string {
	return '(${p.x},${p.y})'
}

interface Drawabler { draw() string }

enum Color { Blue, Green, Red }

fn main() {
	mut lang := 'V!'
	println('Hello $lang')
	lang = 'V will warn you if you dont change mutable variable'
	// Type Cast
	is_true := bool(true) // now variable names cannot contain uppercase letters only snake_case
	println(is_true)
	os := 'linux'
	println(os)
	my_int := int(23)
	println(my_int)
	println(NUMBERS)
	for n in NUMBERS {
		println(n)
	}
	array1 := [2, 4, 5]
	for i := 0; i < 3; i++ {
		println(array1[i])
	}
	switch os {
	case 'darwin':
		println('macOS.')
	case 'linux':
		println('Linux.')
		default:
		println(os)
	}
	p := Point{x: 2, y: 3}
	println(p.draw())

	// show p with str()
	println(p)

	p2 := &Point{x: 7, y: 9}
	println(p2.x)// Pointers have the same syntax for accessing fields
	mut color := Color.Red
	println(color)
	color = Color.Green
  // JSON Decode
	data := '{ "x": 2, "y": 3 }'
	println(data)

	point := json.decode(Point, data) or {
		eprintln('Failed to decode json')
		return
	}
	println(point)
  // Assertion
	assert point.draw() == 'Point(2,3)'

	// Matrices
	m1 := [[2, 4, 5],[5,3,6]]

	// Assertion
	assert m1[0][0] == 2

	// Working with http
	/*html := http.get_text('https://news.ycombinator.com')
	mut pos := 0
	for {
		pos = html.index_after('https://', pos + 1)
		if pos == -1 {
			break
		}
		end := html.index_after('"', pos)
		println(html.substr(pos, end))
	}*/

}