sizefmt

Go Byte Size formatter

This module exposes an int64 alias as Size which can be used for improved size string output with the fmt API.

It supports the following format "verbs":

• %I - SI decimal units: kB(1000), MB(1000²), GB(1000³), TB(1000⁴), PB(1000⁵), EB(1000⁶)
• %B - binary ISO/IEC units: KiB kibibyte(1024), MiB mebibyte(1024²) GiB gibibyte(1024³) TiB tebibyte(1024⁴) PiB pebibyte(1024⁵) EiB exbibyte(1024⁶)
• %J - Binary JDEC units: KB, MB, GB, TB...

They correspond to a hybrid verb corresponding to %d if the value is smaller than 1000 (for SI) or 1024 (for ISO/JDEC) verbs, and that of %f - supporting the same width, precision, signedness and additional flags.

Additionally, we support %s which corresponds to %.2I.

See below for an explanation.

• '+' always print a sign for numeric values
• '-' pad with spaces on the right rather than the left (left-justify the field)
• '#' alternate format: always print a decimal point; if used with %s it uses the corresponding ISO formatting %.2B
• ' ' (space) leave a space for elided sign in numbers (% d); put spaces between bytes printing strings or slices in hex (% x, % X)
• '0' pad with leading zeros rather than spaces; this moves the padding after the sign

We don't support suffixes past Exa due to the fact that values start to overflow the underlying int64 type.

Example:

package main

import (
	"fmt"
	"math"

	bytes "git.sr.ht/~mariusor/sizefmt"
)

func main() {
    const notSoManyBytes = bytes.Size(4096)
    const manyBytes = bytes.Size(math.MaxInt64)

    fmt.Printf("not so many bytes: %.2I %.2B %.2J\n", notSoManyBytes, notSoManyBytes, notSoManyBytes)
    fmt.Printf("so many bytes: %.3I %.3B %.3J", manyBytes, manyBytes, manyBytes)

    // Output: not so many bytes: 4.10kB 4.00KiB 4.00KB
    // so many bytes: 9.223EB 8.000EiB 8.000EB
}