ziglings/exercises/52_slices.zig
2021-03-06 18:20:50 -05:00

49 lines
1.6 KiB
Zig

//
// We've seen that passing arrays around can be awkward. Perhaps you
// remember a particularly horrendous function definition from quiz3?
// This function can only take arrays that are exactly 4 items long!
//
// fn printPowersOfTwo(numbers: [4]u16) void { ... }
//
// That's the trouble with arrays - their size is part of the data
// type and must be hard-coded into every usage of that type. This
// digits array is a [10]u8 forever and ever:
//
// var digits = [10]u8{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
//
// Thankfully, Zig has slices, which let you dynamically point to a
// start item and provide a length. Here are slices of our digit
// array:
//
// const foo = digits[0..1]; // 0
// const bar = digits[3..9]; // 3 4 5 6 7 8
// const all = digits[0..]; // 0 1 2 3 4 5 6 7 8 9
//
// As you can see, a slice [x..y] defines a first item by index x and
// a length y (where y-1 is the index of the last item). Leaving y off
// gives you the rest of the items.
//
// Notice that the type of a slice on an array of u8 items is []u8.
//
const std = @import("std");
pub fn main() void {
var cards = [8]u8{ 'A', '4', 'K', '8', '5', '2', 'Q', 'J' };
// Please put the first 4 cards in hand1 and the rest in hand2.
const hand1: []u8 = cards[???];
const hand2: []u8 = cards[???];
std.debug.print("Hand1: ", .{});
printHand(hand1);
std.debug.print("Hand2: ", .{});
printHand(hand2);
}
// Please lend this function a hand. A u8 slice hand, that is.
fn printHand(hand: ???) void {
for (hand) |h| {
std.debug.print("{u} ", .{h});
}
}