branch.go

package main

import (
	"fmt"
	"io/ioutil"
)

func main() {
	const filename = "abc.txt"
	// if的条件里可以赋值
	// if在条件里赋的值作用域在if语句里
	if contents, err := ioutil.ReadFile(filename); err != nil {
		fmt.Println(err)
	} else {
		fmt.Printf("%s\n", contents)
	}
	fmt.Println(grade(0), grade(10), grade(80), grade(70), grade(160))

	sum := 0
	for i := 1; i <= 100; i++ {
		sum += 1
	}
}



func grade(score int) string {
	g := ""
	switch {
	case score < 0 || score > 100:
		panic(fmt.Sprintf("Wrong score: %d", score))
	case score < 60:
		g = "F"
	case score < 80:
		g = "C"
	case score < 90:
		g = "B"
	case score < 100:
		g = "A"
	}
	return g
}