README
¶
decimal 
Arbitrary-precision fixed-point decimal numbers in go.
NOTE: can "only" represent numbers with a maximum of 2^31 digits after the decmial point.
Features
- the zero-value is 0, and is safe to use without initialization
- addition, subtraction, multiplication with no loss of precision
- division with specified precision
- database/sql serialization/deserialization
- json and xml serialization/deserialization
Install
Run go get github.com/shopspring/decimal
Usage
package main
import (
"fmt"
"github.com/shopspring/decimal"
)
func main() {
price, err := decimal.NewFromString("136.02")
if err != nil {
panic(err)
}
quantity := decimal.NewFromFloat(3)
fee, _ := decimal.NewFromString(".035")
taxRate, _ := decimal.NewFromString(".08875")
subtotal := price.Mul(quantity)
preTax := subtotal.Mul(fee.Add(decimal.NewFromFloat(1)))
total := preTax.Mul(taxRate.Add(decimal.NewFromFloat(1)))
fmt.Println("Subtotal:", subtotal) // Subtotal: 408.06
fmt.Println("Pre-tax:", preTax) // Pre-tax: 422.3421
fmt.Println("Taxes:", total.Sub(preTax)) // Taxes: 37.482861375
fmt.Println("Total:", total) // Total: 459.824961375
fmt.Println("Tax rate:", total.Sub(preTax).Div(preTax)) // Tax rate: 0.08875
}
Documentation
http://godoc.org/github.com/shopspring/decimal
Production Usage
- Spring, since August 14, 2014.
- If you are using this in production, please let us know!
License
The MIT License (MIT)
This is a heavily modified fork of fpd.Decimal, which was also released under the MIT License.
Documentation
¶
Overview ¶
Package decimal implements an arbitrary precision fixed-point decimal.
To use as part of a struct:
type Struct struct {
Number Decimal
}
The zero-value of a Decimal is 0, as you would expect.
The best way to create a new Decimal is to use decimal.NewFromString, ex:
n, err := decimal.NewFromString("-123.4567")
n.String() // output: "-123.4567"
NOTE: This can "only" represent numbers with a maximum of 2^31 digits after the decimal point.
Index ¶
- Variables
- type Decimal
- func (d Decimal) Abs() Decimal
- func (d Decimal) Add(d2 Decimal) Decimal
- func (d Decimal) Cmp(d2 Decimal) int
- func (d Decimal) Div(d2 Decimal) Decimal
- func (d Decimal) Equals(d2 Decimal) bool
- func (d Decimal) Exponent() int32
- func (d Decimal) Float64() (f float64, exact bool)
- func (d Decimal) IntPart() int64
- func (d Decimal) MarshalJSON() ([]byte, error)
- func (d Decimal) MarshalText() (text []byte, err error)
- func (d Decimal) Mul(d2 Decimal) Decimal
- func (d Decimal) Rat() *big.Rat
- func (d *Decimal) Scan(value interface{}) error
- func (d Decimal) String() string
- func (d Decimal) StringScaled(exp int32) string
- func (d Decimal) Sub(d2 Decimal) Decimal
- func (d Decimal) Truncate(precision int32) Decimal
- func (d *Decimal) UnmarshalJSON(decimalBytes []byte) error
- func (d *Decimal) UnmarshalText(text []byte) error
- func (d Decimal) Value() (driver.Value, error)
Constants ¶
This section is empty.
Variables ¶
var DivisionPrecision = 16
DivisionPrecision is the number of decimal places in the result when it doesn't divide exactly.
Example:
d1 := decimal.NewFromFloat(2).Div(decimal.NewFromFloat(3) d1.String() // output: "0.6666666666666667" d2 := decimal.NewFromFloat(2).Div(decimal.NewFromFloat(30000) d2.String() // output: "0.0000666666666667" d3 := decimal.NewFromFloat(20000).Div(decimal.NewFromFloat(3) d3.String() // output: "6666.6666666666666667" decimal.DivisionPrecision = 3 d4 := decimal.NewFromFloat(2).Div(decimal.NewFromFloat(3) d4.String() // output: "0.667"
var Zero = New(0, 1)
Zero constant, to make computations faster.
Functions ¶
This section is empty.
Types ¶
type Decimal ¶
type Decimal struct {
// contains filtered or unexported fields
}
Decimal represents a fixed-point decimal. It is immutable. number = value * 10 ^ exp
func NewFromFloat ¶
NewFromFloat converts a float64 to Decimal.
Example:
NewFromFloat(123.45678901234567).String() // output: "123.4567890123456" NewFromFloat(.00000000000000001).String() // output: "0.00000000000000001"
NOTE: this will panic on NaN, +/-inf
func NewFromFloatWithExponent ¶
NewFromFloatWithExponent converts a float64 to Decimal, with an arbitrary number of fractional digits.
Example:
NewFromFloatWithExponent(123.456, -2).String() // output: "123.46"
func NewFromString ¶
NewFromString returns a new Decimal from a string representation.
Example:
d, err := NewFromString("-123.45")
d2, err := NewFromString(".0001")
func (Decimal) Cmp ¶
Cmp compares the numbers represented by d and d2 and returns:
-1 if d < d2 0 if d == d2 +1 if d > d2
func (Decimal) Div ¶
Div returns d / d2. If it doesn't divide exactly, the result will have DivisionPrecision digits after the decimal point.
func (Decimal) Float64 ¶
Float64 returns the nearest float64 value for d and a bool indicating whether f represents d exactly. For more details, see the documentation for big.Rat.Float64
func (Decimal) MarshalJSON ¶
MarshalJSON implements the json.Marshaler interface.
func (Decimal) MarshalText ¶
MarshalText implements the encoding.TextMarshaler interface for XML serialization.
func (Decimal) String ¶
String returns the string representation of the decimal with the fixed point.
Example:
d := New(-12345, -3) println(d.String())
Output:
-12.345
func (Decimal) StringScaled ¶
StringScaled first scales the decimal then calls .String() on it.
func (Decimal) Truncate ¶
Truncate truncates off digits from the number, without rounding.
NOTE: precision is the last digit that will not be truncated (should be >= 0)
decimal.NewFromString("123.456").Truncate(2).String() // "123.45"
func (*Decimal) UnmarshalJSON ¶
UnmarshalJSON implements the json.Unmarshaler interface.
func (*Decimal) UnmarshalText ¶
UnmarshalText implements the encoding.TextUnmarshaler interface for XML deserialization.
Source Files