What is the correct way to convert a *big.Rat to a int32

[Anindya Chatterjee]

I was porting a java library to go-lang. There I found a piece of java code as follows, for which I could not find any golang equivalent.

BigDecimal bd = new BigDecimal((String)value);

int i = bd != null ? bd.intValue() : Integer.MIN_VALUE;

The closest equivalent to BigDecimal is big.Rat in golang. But big.Rat does not have anything similar to BigDecimal.intValue() to convert to a int32 not even to a big.Int. So what is the best way to achieve the similar result of java's BigDecimal.intValue() in golang?

[Ian Lance Taylor]

If bd is not used later then it looks like you want strconv.ParseInt.
I don't know why the Java code bothers to use a BigDecimal.

To convert a big.Rat to int do something like
f, _ := r.Float64()
i := int(f)

Ian

[Ben Hood]

Is inf.Dec an option for you?

https://speter.net/go/exp/math/dec/inf

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[Anindya Chatterjee]

Thanks for the link, but I think I am stuck here again with the same problem. How to convert *Dec to int32? Unless you meant to take the route of :

• func (x *Dec) UnscaledBig() *big.Int

It is more or less similar of using *big.Rat I guess. In case I am misunderstood, please rectify me.

[Michael Jones]

You could simply do a big int divide of the rat's numerator by its denominator. That is the integer value...

[Ben Hood]

On Fri, May 16, 2014 at 7:52 PM, Anindya Chatterjee <anid...@gmail.com> wrote:
> Thanks for the link, but I think I am stuck here again with the same
> problem. How to convert *Dec to int32? Unless you meant to take the route of
> :
>
> func (x *Dec) UnscaledBig() *big.Int
>
>
> It is more or less similar of using *big.Rat I guess. In case I am
> misunderstood, please rectify me.

I'm not 100% sure this will solve your issue, but inf.Dec does expose
the Unscaled() function to return an int64:

http://godoc.org/speter.net/go/exp/math/dec/inf#Dec.Unscaled

As for your int32, you could narrow the int64 to an int32, but the
things might not be be the same, which might not be helpful in your
scenario.