main.go 源码
// Copyright © 2018 Inanc Gumus
// Learn Go Programming Course
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
//
// For more tutorials : https://learngoprogramming.com
// In-person training : https://www.linkedin.com/in/inancgumus/
// Follow me on twitter: https://twitter.com/inancgumus
package main
import "fmt"
func main() {
// zero-values
var (
planet string
distance int
orbital float64
hasLife bool
)
// assignment
planet = "venus"
distance = 261
orbital = 224.701
hasLife = false
// var (
// planet = "venus"
// distance = 261
// orbital = 224.701
// hasLife = false
// )
distance += 5
distance *= 2
distance++
distance--
orbital++
// orbital *= 10
const constFactor = 10
orbital *= constFactor
factor := 10
// orbital *= factor
orbital *= float64(factor)
// swiss army knife %v verb
fmt.Printf("Planet: %v\n", planet)
fmt.Printf("Distance: %v millions kms\n", distance)
fmt.Printf("Orbital Period: %v days\n", orbital)
fmt.Printf("Does %v have life? %v\n", planet, hasLife)
// argument indexing - indexes start from 1
fmt.Printf(
"%v is %v away. Think! %[2]v kms! %[1]v OMG.\n",
planet, distance,
)
// why use other verbs than? because: type-safety
// uncomment to see the warnings:
//
// fmt.Printf("Planet: %d\n", planet)
// fmt.Printf("Distance: %s millions kms\n", distance)
// fmt.Printf("Orbital Period: %t days\n", orbital)
// fmt.Printf("Does %v has life? %f\n", planet, hasLife)
// correct verbs:
// fmt.Printf("Planet: %s\n", planet)
// fmt.Printf("Distance: %d millions kms\n", distance)
// fmt.Printf("Orbital Period: %f days\n", orbital)
// fmt.Printf("Does %s has life? %t\n", planet, hasLife)
// precision
fmt.Printf("Orbital Period: %f days\n", orbital)
fmt.Printf("Orbital Period: %.0f days\n", orbital)
fmt.Printf("Orbital Period: %.1f days\n", orbital)
fmt.Printf("Orbital Period: %.2f days\n", orbital)
}
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