在Golang中，如何将切片转换为数组

Question

I am new to Go and trying to write an application that reads RPM files. The start of each block has a Magic char of [4]byte.

Here is my struct

type Lead struct {
  Magic        [4]byte
  Major, Minor byte
  Type         uint16
  Arch         uint16
  Name         string
  OS           uint16
  SigType      uint16
}

I am trying to do the following:

lead := Lead{}
lead.Magic = buffer[0:4]

I am searching online and not sure how to go from a slice to an array (without copying). I can always make the Magic []byte (or even uint64), but I was more curious on how would I go from type []byte to [4]byte if needed to?

Answer 1

The built in method copy will only copy a slice to a slice NOT a slice to an array.

You must trick copy into thinking the array is a slice

copy(varLead.Magic[:], someSlice[0:4])

Or use a for loop to do the copy:

for index, b := range someSlice {

    varLead.Magic[index] = b

}

Or do as zupa has done using literals. I have added onto their working example.

Go Playground