go-why-use-bit-wise-iota

why use << iota?

tags: learning go programming

content

• in go-iota-with-bit-shift-operator, im seeing something like:

const (
    FlagA = 1 << iota   // 1  (binary: 0001)
    FlagB               // 2  (binary: 0010)
    FlagC               // 4  (binary: 0100)
    FlagD               // 8  (binary: 1000)
)

• why do we wanna use these, other than normal iota?

  • one use case is to combine flags!

• we can now use bit-wise OR operation, or | in Go’s syntax, to combine flags!

myFlags := FlagA | FlagB

• binary wise, myFlag becomes 0011

• decimal wise, myFlag become 3 (but of course, we don’t use decimal in this case, it’s not particularly useful)

• to check if myFlags contains FlagA:

  • we need to check if myFlags AND FlagA is all 0000

myFlags  0011
FlagA    0001
--------------
AND      0001

• translate to Go’s syntax:

if myFlags & FlagA == FlagA:

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