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"
"os"
"strconv"
)
func main() {
// lesson: switch
if len(os.Args) != 4 {
fmt.Println("Usage: calc <number1> <operator> <number2>")
return
}
a, err := strconv.ParseFloat(os.Args[1], 64)
if err != nil {
fmt.Println("Please provide a valid number")
return
}
b, err := strconv.ParseFloat(os.Args[3], 64)
if err != nil {
fmt.Println("Please provide a valid number")
return
}
// multiple declare
var (
// declare & assign
op = os.Args[2]
res float64
)
switch op {
case "+":
res = a + b
case "-":
res = a - b
case "*":
res = a * b
case "/":
res = a / b
}
fmt.Printf("%v %v %v = %v\n", a, op, b, res)
}
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