Go中的惯用类型转换

Question

I was playing around with Go and was wondering what the best way is to perform idiomatic type conversions in Go. Basically my problem lays within automatic type conversions between uint8, uint64, and float64. From my experience with other languages a multiplication of a uint8 with a uint64 will yield a uint64 value, but not so in go.

Here is an example that I build and I ask if this is the idiomatic way of writing this code or if I'm missing an important language construct.

package main

import ("math";"fmt")

const(Width=64)

func main() {

    var index uint32
    var bits uint8

    index = 100
    bits = 3

    var c uint64
    // This is the line of interest vvvv
    c = uint64(math.Ceil(float64(index * uint32(bits))/float64(Width)))
    fmt.Println("Test: %v
", c)
}

From my point of view the calculation of the ceiling value seems unnecessary complex because of all the explicit type conversions.

Thanks!

Answer 1

There are no implicit type conversions for non-constant values.

You can write

var x float64
x = 1

But you cannot write

var x float64
var y int

y = 1
x = y

See the spec for reference.

There's a good reason, to not allow automatic/implicit type conversions, as they can become very messy and one has to learn many rules to circumvent the various caveats that may occur. Take the Integer Conversion Rules in C for example.