问题描述
目前,我这样做是为了将CGO的double数组转换为float64切片:
doubleSlc := [6]C.double{}
// Fill doubleSlc
floatSlc := []float64{float64(doubleSlc[0]), float64(doubleSlc[1]), float64(doubleSlc[2]),
float64(doubleSlc[3]), float64(doubleSlc[4]), float64(doubleSlc[5])}
做同样的事情有没有那么麻烦的方法?我想这也可以看作是Go中不同类型的切片/数组之间进行转换的一种通用方法.
您拥有正常且安全的方法:
c := [6]C.double{ 1, 2, 3, 4, 5, 6 }
fs := make([]float64, len(c))
for i := range c {
fs[i] = float64(c[i])
}
或者您也可以作弊,并且这样做:
c := [6]C.double{ 1, 2, 3, 4, 5, 6 }
cfa := (*[6]float64)(unsafe.Pointer(&c))
cfs := cfa[:]
如果C.double
和float64
是相同的基础类型,我们可以采用指向C.double数组的指针,不安全地将其强制转换为相同大小的float64数组的指针,然后采用该数组的一个切片. /p>
当然,有很好的理由将其称为unsafe
.
At the moment I do this for casting a CGO array of doubles into a slice of float64:
doubleSlc := [6]C.double{}
// Fill doubleSlc
floatSlc := []float64{float64(doubleSlc[0]), float64(doubleSlc[1]), float64(doubleSlc[2]),
float64(doubleSlc[3]), float64(doubleSlc[4]), float64(doubleSlc[5])}
Is there a less cumbersome way of doing the same thing? I suppose this can also be seen as a general way of casting between slices/arrays of different types in Go.
You have the normal and safe way of doing this:
c := [6]C.double{ 1, 2, 3, 4, 5, 6 }
fs := make([]float64, len(c))
for i := range c {
fs[i] = float64(c[i])
}
Or you could cheat unportably and do this:
c := [6]C.double{ 1, 2, 3, 4, 5, 6 }
cfa := (*[6]float64)(unsafe.Pointer(&c))
cfs := cfa[:]
If C.double
and float64
are the same underlying type we can take a pointer to the C.double array, unsafely cast it to a pointer to a same size float64 array, then take a slice of that array.
Of course it's called unsafe
for a very good reason.
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