76 lines
1.4 KiB
Go
76 lines
1.4 KiB
Go
// 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 (
|
|
"errors"
|
|
"fmt"
|
|
"os"
|
|
"strconv"
|
|
)
|
|
|
|
func main() {
|
|
// lesson: many - split this
|
|
|
|
if len(os.Args) != 4 {
|
|
fmt.Println("Usage: calc <number1> <operator> <number2>")
|
|
return
|
|
}
|
|
|
|
var (
|
|
a, b float64
|
|
err error
|
|
)
|
|
|
|
if a, err = parse(os.Args[1]); err != nil {
|
|
fmt.Println(err)
|
|
return
|
|
}
|
|
|
|
if b, err = parse(os.Args[3]); err != nil {
|
|
fmt.Println(err)
|
|
return
|
|
}
|
|
|
|
op := os.Args[2]
|
|
res, err := calc(a, b, op)
|
|
if err != nil {
|
|
fmt.Println(err)
|
|
return
|
|
}
|
|
|
|
fmt.Printf("%v %s %v = %v\n", a, op, b, res)
|
|
}
|
|
|
|
func parse(snum string) (n float64, err error) {
|
|
n, err = strconv.ParseFloat(snum, 64)
|
|
if err != nil {
|
|
err = errors.New("Please provide a valid number")
|
|
}
|
|
return
|
|
}
|
|
|
|
func calc(a, b float64, op string) (res float64, err error) {
|
|
switch op {
|
|
case "+", "plus":
|
|
op, res = "+", a+b
|
|
case "-", "minus":
|
|
op, res = "-", a-b
|
|
case "*", "times":
|
|
op, res = "*", a*b
|
|
case "/", "div":
|
|
op, res = "/", a/b
|
|
case "%", "mod":
|
|
res = float64(int(a) % int(b))
|
|
default:
|
|
return 0, errors.New("Wrong operation: '" + op + "'")
|
|
}
|
|
return
|
|
}
|