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money notation #95

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money notation #95

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8e799e8
add: .gitignore
lfaoro Aug 28, 2021
308d7d1
add: finance implementation and tests
lfaoro Aug 29, 2021
b6630c4
Revert "add: .gitignore"
lfaoro Oct 8, 2021
43a0dc8
add: FinanceSign variable to allow users change currency symbol
lfaoro Oct 8, 2021
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50 changes: 50 additions & 0 deletions finance.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
package humanize

import (
"fmt"
)

var (
FinanceSign = "$"
)

func Finance(f float64) string {
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I wonder if it would make sense to take some optional Options which could set things like which $ sign to use and if it should be prepended or appended (or omitted entirely) and could control the # of decimal points.

So you could do things like:

  1. 1.83M USD
  2. €2.34T
  3. 48.9945

etc. Could also look at the various locales used with https://www.php.net/manual/en/function.money-format.php

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@lfaoro lfaoro Sep 27, 2021 •
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Very good idea, I'll add the Options pattern, the options will be:

  • WithSign(s string) // can pass "" to remove the default ($) sign
  • WithAppend() // if no append, Prepend is default -- otherwise could add both options
  • WithPrecision(n int) // defaults to .2

WDYT?

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ping @harrisonhjones

switch n := f; {
case n >= 1_000_000_000_000_000:
s := fmt.Sprintf("%.f", f)
s = insertAt(1, '.', []rune(s[:4]))
return fmt.Sprintf("%s%sQ", FinanceSign, s)

case n >= 1_000_000_000_000:
s := fmt.Sprintf("%.f", f)
s = insertAt(1, '.', []rune(s[:4]))
return fmt.Sprintf("%s%sT", FinanceSign, s)

case n >= 1_000_000_000:
s := fmt.Sprintf("%.f", f)
s = insertAt(1, '.', []rune(s[:4]))
return fmt.Sprintf("%s%sB", FinanceSign, s)

case n >= 1_000_000:
s := fmt.Sprintf("%.f", f)
s = insertAt(1, '.', []rune(s[:4]))
return fmt.Sprintf("%s%sM", FinanceSign, s)

case n >= 1_000:
s := fmt.Sprintf("%.f", f)
s = insertAt(1, '.', []rune(s[:4]))
return fmt.Sprintf("%s%sK", FinanceSign, s)

case n < 1_000:
return fmt.Sprintf("%s%.f", FinanceSign, f)

default:
return "NaN"
}
}

func insertAt(index int, elem rune, slice []rune) string {
copy(slice[index+1:], slice[index:])
slice[index] = elem
return string(slice)
}
30 changes: 30 additions & 0 deletions finance_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
package humanize

import (
"math"
"testing"
)

func TestFinance(t *testing.T) {
tests := []struct {
name string
arg float64
want string
}{
{"Quadrillions", 2_475_260_494_216_000, "$2.47Q"},
{"Trillions", 2_475_260_494_216, "$2.47T"},
{"Billions", 2_475_260_494, "$2.47B"},
{"Millions", 2_475_260, "$2.47M"},
{"Thousands", 2_475, "$2.47K"},
{"Hundreds", 247, "$247"},
{"Tens", 24, "$24"},
{"NaN", math.NaN(), "NaN"},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if got := Finance(tt.arg); got != tt.want {
t.Errorf("Finance() = %v, want %v", got, tt.want)
}
})
}
}