Format money for a receipt
The receipt printer takes a plain string. Amounts arrive in minor units and have to come out grouped and signed the way finance expects.
- Always two decimal places.
- Group the whole part in threes with commas: 123456 becomes 1,234.56.
- Negatives are wrapped in parentheses with no minus sign, so -50 becomes (0.50).
formatMoney(minor: int) → string
Go needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
func formatMoney(minor int) string {
}Worked examples
| Call | Result |
|---|---|
formatMoney(123456) | "1,234.56" |
formatMoney(0) | "0.00" |
formatMoney(5) | "0.05" |
formatMoney(-50) | "(0.50)" |
Hint
Split into whole and remainder first, build the grouped whole part, then glue on the sign.
Reference solution in Go
func formatMoney(minor int) string {
neg := minor < 0
abs := minor
if abs < 0 {
abs = -abs
}
whole := strconv.Itoa(abs / 100)
cents := strconv.Itoa(abs % 100)
if len(cents) < 2 {
cents = "0" + cents
}
grouped := ""
for i := 0; i < len(whole); i++ {
if i > 0 && (len(whole)-i)%3 == 0 {
grouped += ","
}
grouped += string(whole[i])
}
body := grouped + "." + cents
if neg {
return "(" + body + ")"
}
return body
}