base62
base62 implements base62 encoding for integer numbers of arbitrary precision.
Currently both int64 and *big.Int are supported
Encoding
The encoding is different to base64 encoding in two ways:
- Reduced character set, without symbols -
0-9A-Za-z - Character ordering - base64 is
A-Za-z0-9
Note that this character ordering is also different to most other base62 encodings, but preserves the sort order of encoded values.
As a result, the encoded strings can be lexically sorted if either a sorting order such as shortlex is used, or if the resulting strings are left padded to ensure a consistent length.
Usage
First go get the package:
go get github.com/mattheath/base62
This can then be used as below:
package main
import (
"fmt"
"math/big"
"github.com/mattheath/base62"
)
func main() {
// Encoding 64 bit integers
var n int64 = 4815162342
encoded := base62.EncodeInt64(n)
fmt.Println(encoded) // prints 5Frvgk
// Arbitrary precision integers can be specified using the math/big pkg
var b *big.Int = new(big.Int)
b.SetString("340282366920938463463374607431768211455") // 128bit unsigned int
bigEncoded := base62.EncodeBigInt(b)
fmt.Println(bigEncoded) // prints 7n42DGM5Tflk9n8mt7Fhc7
// Padding can be specified using an option on an Encoding
// eg. to pad strings to a minimum length of 15 chars:
e := base62.NewStdEncoding().Option(Padding(15))
encoded = e.EncodeInt64(n)
fmt.Println(encoded) // prints 0000000005Frvgk
}
