Documentation
¶
Overview ¶
Package unitconv implements string conversion functionality for unit prefixes such as those from the SI and IEC standards.
Index ¶
Examples ¶
Constants ¶
const ( Kibi = 1 << 10 Mebi = 1 << 20 Gibi = 1 << 30 Tebi = 1 << 40 Pebi = 1 << 50 Exbi = 1 << 60 Zebi = 1 << 70 Yobi = 1 << 80 )
Prefix factors according to IEC standards.
const ( Yocto = 1e-24 Zepto = 1e-21 Atto = 1e-18 Femto = 1e-15 Pico = 1e-12 Nano = 1e-9 Micro = 1e-6 Milli = 1e-3 Unit = 1e0 // Not a standard SI prefix. Kilo = 1e+3 Mega = 1e+6 Giga = 1e+9 Tera = 1e+12 Peta = 1e+15 Exa = 1e+18 Zetta = 1e+21 Yotta = 1e+24 )
Prefix factors according to SI standards.
Variables ¶
This section is empty.
Functions ¶
func AppendPrefix ¶
AppendPrefix appends the string form of the floating-point number val, as generated by FormatPrefix, to dst and returns the extended buffer.
Example ¶
package main
import (
"fmt"
"github.com/dsnet/golib/unitconv"
)
func main() {
b1 := []byte("Distance from SF to LA: ")
b1 = unitconv.AppendPrefix(b1, 616379, unitconv.SI, -1)
b1 = append(b1, 'm')
fmt.Println(string(b1))
b2 := []byte("Capacity of a DVD: ")
b2 = unitconv.AppendPrefix(b2, 4.7*unitconv.Giga, unitconv.IEC, 2)
b2 = append(b2, 'B')
fmt.Println(string(b2))
}
Output: Distance from SF to LA: 616.379km Capacity of a DVD: 4.38GiB
func FormatPrefix ¶
FormatPrefix converts the floating-point number val to a string, according to the prefix notation specified by mode. The prec specifies the precision used by the numeric portion.
Even if prec is -1, formatting a value and parsing it does not guarantee that the exact value will be returned. It will however be extremely accurate.
It is valid to format +Inf, -Inf, and NaN.
Example ¶
package main
import (
"fmt"
"github.com/dsnet/golib/unitconv"
)
func main() {
s1 := unitconv.FormatPrefix(unitconv.Tebi, unitconv.SI, 3)
fmt.Printf("1 tebibyte in SI: %sB\n", s1)
s2 := unitconv.FormatPrefix(unitconv.Tera, unitconv.IEC, 3)
fmt.Printf("1 terabyte in IEC: %sB\n", s2)
}
Output: 1 tebibyte in SI: 1.100TB 1 terabyte in IEC: 931.323GiB
func ParsePrefix ¶
ParsePrefix converts the string str to a floating-point number, according to the prefix notation specified by mode.
It is valid to parse +Inf, -Inf, and NaN.
Example ¶
package main
import (
"fmt"
"github.com/dsnet/golib/unitconv"
)
func main() {
if s, err := unitconv.ParsePrefix("2.99792458E8", unitconv.AutoParse); err == nil {
fmt.Printf("Speed of light: %.0fm/s\n", s)
}
if s, err := unitconv.ParsePrefix("616.379k", unitconv.SI); err == nil {
fmt.Printf("Distance from LA to SF: %.0fm\n", s)
}
if s, err := unitconv.ParsePrefix("32M", unitconv.Base1024); err == nil {
fmt.Printf("Max FAT12 partition size: %.0fB\n", s)
}
if s, err := unitconv.ParsePrefix("1Ti", unitconv.IEC); err == nil {
fmt.Printf("Number of bytes in tebibyte: %.0fB\n", s)
}
}
Output: Speed of light: 299792458m/s Distance from LA to SF: 616379m Max FAT12 partition size: 33554432B Number of bytes in tebibyte: 1099511627776B
Types ¶
type Mode ¶
type Mode int
Mode is the base conversion for strings.
const ( // AutoParse will parse the input as either the SI, IEC, or regular float // notation as accepted by ParseFloat. // // This is an invalid mode for Append and Format. AutoParse Mode = iota // SI uses a scaling of 1000x, and uses a single letter symbol to denote // the scaling. The prefixes ranges from Yocto (1E-24) to Yotta (1E+24). // // The output uses SI prefixes, and uses 'k' for Kilo and 'μ' for Micro. // The input accepts SI prefixes along with 'k' and 'K' for Kilo and // 'μ' and 'u' for Micro. // It does not support the Deca, Hecto, Deci, or Centi prefixes. SI // Base1024 uses a scaling of 1024x, but uses the same prefixes as SI. This // is a non-standard prefix notation and exists because many legacy systems // unfortunately operate in this way. // // The output uses SI prefixes, but uses 'K' for Kilo and 'u' for Micro. // The input accepts SI prefixes along with 'k' and 'K' for Kilo and // 'μ' and 'u' for Micro. It also accepts IEC notation. Base1024 // IEC uses a scaling of 1024x, and uses a two-letter symbol to denote the // scaling in a system similar to SI. Instead of Kilo denoted as 'k', it // uses Kibi denoted as 'Ki'. The prefixes ranges from Unit (1) to Yobi // (1<<80). Representing values less than 1 will not use any of the divisor // prefixes. IEC notation is easy to identify since the prefix symbols // always end with the letter 'i'. // // The output uses IEC prefixes that are Unit and greater. // The input accepts IEC prefixes only. IEC )
These are the different modes for Prefix string conversion.
Source Files