Fun with floating point precision in Go

floats.go

package main

import (
	"fmt"
	"math/big"
)

func main() {
	var a, b, c float32

	// The bad way
	a = 0.1
	b = 0.2
	c = a * b

	fmt.Println(c)
	fmt.Println(a * b)

	// The "with Go don't go that way" way
	d := 0.1 * 0.2
	fmt.Println(d)

	fmt.Println(0.1 * 0.2)

	// The good way
	m := big.NewFloat(0.1)
	n := big.NewFloat(0.2)
	var o big.Float
	//take care that o is of a different type than m and n (big.Float vs *big.Float)
	o.Mul(m, n)
	fmt.Println(o.String())

	/* ==>
	0.020000001
	0.020000001
	0.02
	0.02
	0.02
	*/

}