RosettaCodeData/Task/Number-names/Go/number-names.go

59 lines
1.1 KiB
Go

package main
import "fmt"
func main() {
for _, n := range []int64{12, 1048576, 9e18, -2, 0} {
fmt.Println(say(n))
}
}
var small = [...]string{"zero", "one", "two", "three", "four", "five", "six",
"seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen",
"fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"}
var tens = [...]string{"", "", "twenty", "thirty", "forty",
"fifty", "sixty", "seventy", "eighty", "ninety"}
var illions = [...]string{"", " thousand", " million", " billion",
" trillion", " quadrillion", " quintillion"}
func say(n int64) string {
var t string
if n < 0 {
t = "negative "
// Note, for math.MinInt64 this leaves n negative.
n = -n
}
switch {
case n < 20:
t += small[n]
case n < 100:
t += tens[n/10]
s := n % 10
if s > 0 {
t += "-" + small[s]
}
case n < 1000:
t += small[n/100] + " hundred"
s := n % 100
if s > 0 {
t += " " + say(s)
}
default:
// work right-to-left
sx := ""
for i := 0; n > 0; i++ {
p := n % 1000
n /= 1000
if p > 0 {
ix := say(p) + illions[i]
if sx != "" {
ix += " " + sx
}
sx = ix
}
}
t += sx
}
return t
}