Big.Int Div always returns 0

Question

I am unable to get a value when using BigInt.Div() in Go.

Big Ints:

    totalAllocPoint, _ := instance_polypup.TotalAllocPoint(&bind.CallOpts{}) //*big.int
    fmt.Println("totalAllocPoint: ", totalAllocPoint)// 54000

    poolInfoStruct, _ := instance_polypup.PoolInfo(&bind.CallOpts{}, &pid) //*big.int
    fmt.Println("allocPoint: ", poolInfoStruct.AllocPoint)// 2000

I have tried to divide using the following code, always returns 0:

    poolInfoStruct.AllocPoint.Div(poolInfoStruct.AllocPoint, totalAllocPoint)
    fmt.Println("poolAlloc: ", poolInfoStruct.AllocPoint)

    poolAlloc := big.NewInt(0).Div(poolInfoStruct.AllocPoint, totalAllocPoint)
    fmt.Println("poolAlloc: ", poolAlloc)

    poolAlloc := big.NewInt(0)
    poolAlloc.Div(poolInfoStruct.AllocPoint, totalAllocPoint)
    fmt.Println("poolAlloc: ", poolAlloc)

Answer 1

Int.Div() is an integer division operation. And you divide poolInfoStruct.AllocPoint by totalAllocPoint which is 2000 / 54000. That will always be 0, because the divisor is greater than the dividend.

Maybe you want the opposite? totalAllocPoint / poolInfoStruct.AllocPoint

See this example:

totalAllocPoint := big.NewInt(54000)
allocPoint := big.NewInt(2000)

totalAllocPoint.Div(totalAllocPoint, allocPoint)
fmt.Println(totalAllocPoint)

Which output 27 (try it on the Go Playground).

You indicated that divisor and dividend are correct. If so, you cannot use big.Int for this, as big.Int can only represent integers.

You may use big.Float for this for example, and use Float.Quo() to calculate the quotient.

For example:

totalAllocPoint := big.NewInt(54000)
allocPoint := big.NewInt(2000)

tot := big.NewFloat(0).SetInt(totalAllocPoint)
ap := big.NewFloat(0).SetInt(allocPoint)

tot.Quo(ap, tot)
fmt.Println(tot)

Output (try it on the Go Playground):

0.037037037037037035

Another option is to use big.Rat and Rat.Quo():

tot := big.NewRat(0, 1).SetInt(totalAllocPoint)
ap := big.NewRat(0, 1).SetInt(allocPoint)

tot.Quo(ap, tot)
fmt.Println(tot)

Output (try it on the Go Playground):

1/27