Convert integers between different bases

intconv.go

package main

import (
	"flag"
	"fmt"
	"github.com/clsr/intcodec"
	"os"
	"strings"
)

var (
	inBase = flag.Int("i", 10, "the base of the input numbers")
	outBase = flag.Int("o", 10, "the base of the output numbers")

	upper = flag.Bool("u", false, "use uppercase letters in the output")
)

func main() {
	flag.Parse()
	in := intcodec.LowerBaseN(*inBase)
	var out *intcodec.Codec
	if *upper {
		out = intcodec.UpperBaseN(*outBase)
	} else {
		out = intcodec.LowerBaseN(*outBase)
	}

	for _, arg := range flag.Args() {
		n, err := in.DecodeInt(strings.ToLower(arg))
		if err != nil {
			fmt.Fprintf(os.Stderr, "error: %s\n", err)
			os.Exit(1)
		}
		fmt.Println(out.EncodeInt(n))
	}
}