Got a card of Rank = 0, is that right? about decks

[preslavmihaylov]

Card of Rank 0 is Ace.

decks/deck.go

Line 29 in 9e34f47

const (

Note that the ranks do not necessarily correspond to the values of a card - e.g. 1 for Ace, as those are different for every game.

If you want to add values to a card, I suggest writing a custom function in your own package. Something like valueOf(c decks.Card).

And if you want to check whether a card you got is of a certain rank, you can do:

if (c.Rank == decks.Ace) {
    // handle Ace
}

Or a range:

if (c.Rank >= decks.Two && c.Rank < decks.Ten) {
    // handle cards [2, 10)
}

[dcu]

why not starting in iota+1? that would cover the value for most cases

[preslavmihaylov]

The initial implementation used that, yes.

But eventually, I decided to change it as it is now, because that approach causes issues with iterating over cards.

If the Ace starts at value 1, not zero, then there are all sorts of off-by-one errors that could occur.
For example, let's say you want to iterate over all ranks. Intuitively, you might do something like this:

cards := make([]Card, decks.RanksCnt)
for i := 0; i < decks.RanksCnt; i++ {
    cards[i] = decks.Card{Rank: i}
}

Issues with the code above if Ace starts at 1:

1. Rank of zero is invalid
2. You won't include the last rank (King)

Even if you do:

cards := make([]Card, decks.RanksCnt)
for i := decks.Ace; i < decks.RanksCnt; i++ {
    cards[i] = decks.Card{Rank: i}
}

This is still wrong, because you will miss the last rank (King) as decks.King == decks.RanksCnt