Dirty calculator

FileCalculatorKata.go

package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
	"strconv"
)

func main() {
	filePath := os.Args[1]
	operator := os.Args[2]
	var numbers []int

	file, err := os.Open(filePath)
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		number, err := strconv.Atoi(scanner.Text())
		if err != nil {
			log.Fatal(err)
		}
		numbers = append(numbers, number)
	}

	if err := scanner.Err(); err != nil {
		log.Fatal(err)
	}
	total := 0
	for k, v := range numbers {
		if k == 0 {
			total = v
			fmt.Println(v)
		} else {
			switch operator {
			case "+":
				total += v
			case "*":
				total *= v
			}
			fmt.Printf("%s%d (=%d)\n", operator, v, total)
		}
	}
	operatorStr := ""
	switch operator {
	case "+":
		operatorStr = "addition"
	case "*":
		operatorStr = "multiplication"
	}

	fmt.Println("-------")
	fmt.Printf("total = %d (%s)\n", total, operatorStr)
}