Swift: How to use sizeof?

Question

In order to integrate with C API\'s while using Swift, I need to use the sizeof function. In C, this was easy. In Swift, I am in a labyrinth of type errors.

I have

Answer 1

Swift 4

From Xcode 9 onwards there is now a property called .bitWidth, this provides another way of writing sizeof: functions for instances and integer types:

func sizeof(_ int:T) -> Int {
    return int.bitWidth/UInt8.bitWidth
}

func sizeof(_ intType:T.Type) -> Int {
    return intType.bitWidth/UInt8.bitWidth
}

sizeof(UInt16.self) // 2
sizeof(20) // 8

But it would make more sense for consistency to replace sizeof: with .byteWidth:

extension FixedWidthInteger {
    var byteWidth:Int {
        return self.bitWidth/UInt8.bitWidth
    }
    static var byteWidth:Int {
        return Self.bitWidth/UInt8.bitWidth
    }
}

1.byteWidth // 8
UInt32.byteWidth // 4

It is easy to see why sizeof: is thought ambiguous but I'm not sure that burying it in MemoryLayout was the right thing to do. See the reasoning behind the shifting of sizeof: to MemoryLayout here.