util.go

package l0la

import (
	"fmt"
	"strconv"
)

func FGroup(n int) string {
	in := strconv.FormatInt(int64(n), 10)
	numOfDigits := len(in)
	if n < 0 {
		numOfDigits-- // First character is the - sign (not a digit)
	}
	numOfCommas := (numOfDigits - 1) / 3

	out := make([]byte, len(in)+numOfCommas)
	if n < 0 {
		in, out[0] = in[1:], '-'
	}

	for i, j, k := len(in)-1, len(out)-1, 0; ; i, j = i-1, j-1 {
		out[j] = in[i]
		if i == 0 {
			return string(out)
		}
		if k++; k == 3 {
			j, k = j-1, 0
			out[j] = ','
		}
	}
}

func LPad(n int, v string) string {
	if len(v) < n {
		f := fmt.Sprintf("%%%ds", n)
		return fmt.Sprintf(f, v)
	} else {
		return v
	}
}