Big number to HEX in golang

Question

I'm trying to convert big numbers (big.Int or even better big.Rat) to hex values.

I'm always having issue converting number when they are negative 0xff..xx or Fixed numbers.

Is there a way to do that?

Answer 1

Not sure what kind of issues are you having, but big.Int, big.Float and big.Rat implement the fmt.Formatter interface, you can use the printf family with the %x %X to convert to hexadecimal string representation, example:

package main

import (
    "fmt"
    "math/big"
)

func toHexInt(n *big.Int) string {
    return fmt.Sprintf("%x", n) // or %x or upper case
}

func toHexRat(n *big.Rat) string {
    return fmt.Sprintf("%x", n) // or %x or upper case
}

func main() {
    a := big.NewInt(-59)
    b := big.NewInt(59)

    fmt.Printf("negative int lower case: %x\n", a)
    fmt.Printf("negative int upper case: %X\n", a) // %X for upper case

    fmt.Println("using Int function:", toHexInt(b))

    f := big.NewRat(3, 4) // fraction: 3/4

    fmt.Printf("rational lower case: %x\n", f)
    fmt.Printf("rational lower case: %X\n", f)

    fmt.Println("using Rat function:", toHexRat(f))
}

https://play.golang.org/p/BVh7wAYfbF