I am trying to format some numbers as a currency, with commas and 2 decimal places. I've found "github.com/dustin/go-humanize" for the commas but it doesn't allow for specifying the number of decimal places. fmt.Sprintf will do the currency and decimal formatting but not the commas.
for _, fl := range []float64{123456.789, 123456.0, 123456.0100} {
log.Println(humanize.Commaf(fl))
}
Results:
123,456.789
123,456
123,456.01
I am expecting:
$123,456.79
$123,456.00
$123,456.01
There is a good blog post about why you should never use floats to represent currency here - http://engineering.shopspring.com/2015/03/03/decimal/
From their examples you can :
d := New(-12345, -3)
println(d.String())
Will give you :
-12.345
fmt.Printf("%.2f", 12.3456)
-- output is 12.34
That would be what the humanize.FormatFloat() does:
// FormatFloat produces a formatted number as string based on the following user-specified criteria:
// * thousands separator
// * decimal separator
// * decimal precision
In your case:
FormatFloat("$#,###.##", afloat)
That being said, as commented by LenW, float (in Go, float64) is not a good fit for currency.
See floating-point-gui.de.
Using a package like go-inf/inf (previously go/dec, used for instance in this currency implementation) is better.
See Dec.go:
// A Dec represents a signed arbitrary-precision decimal.
// It is a combination of a sign, an arbitrary-precision integer coefficient
// value, and a signed fixed-precision exponent value.
// The sign and the coefficient value are handled together as a signed value
// and referred to as the unscaled value.
That type Dec does include a Format() method.
Since July 2015, you now have leekchan/accounting from Kyoung-chan Lee (leekchan) with the same advice:
Please do not use
float64to count money. Floats can have errors when you perform operations on them.
Usingbig.Rat(< Go 1.5) orbig.Float(>= Go 1.5) is highly recommended. (accounting supportsfloat64, but it is just for convenience.)
fmt.Println(ac.FormatMoneyBigFloat(big.NewFloat(123456789.213123))) // "$123,456,789.21"
Try:
ToString("#,##0.00");
or you can try this too:
int number = 1234567890;
Convert.ToDecimal(number).ToString("#,##0.00");
You will get the result like this 1,234,567,890.00.