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| -rw-r--r-- | build.zig | 4 | ||||
| -rw-r--r-- | exercises/54_multipointers.zig | 53 |
2 files changed, 57 insertions, 0 deletions
@@ -276,6 +276,10 @@ const exercises = [_]Exercise{ .main_file = "53_slices2.zig", .output = "'all your base are belong to us.' 'for great justice.'", }, + .{ + .main_file = "54_multipointers.zig", + .output = "Memory is a resource.", + }, }; /// Check the zig version to make sure it can compile the examples properly. diff --git a/exercises/54_multipointers.zig b/exercises/54_multipointers.zig new file mode 100644 index 0000000..b6fb1f7 --- /dev/null +++ b/exercises/54_multipointers.zig @@ -0,0 +1,53 @@ +// +// You can also make pointers to multiple items without using a slice. +// +// var foo: [4]u8 = [4]u8{ 1, 2, 3, 4 }; +// var foo_slice: []u8 = foo[0..]; +// var foo_ptr: [*]u8 = &foo; +// +// The difference between foo_slice and foo_ptr is that the slice has +// a known length. The pointer doesn't. It is up to YOU to keep track +// of the number of u8s foo_ptr points to! +// +const std = @import("std"); + +pub fn main() void { + // Take a good look at the type of the zen12 string: + const zen12: *const [21]u8 = "Memory is a resource."; + // It would also have been valid to coerce this to a slice: + // + // const zen12: []const u8 = "..."; + // + // Now let's turn this into a "multi pointer": + const zen_multiptr: [*]const u8 = zen12; + + // It's okay to access zen_multiptr just like an array or slice as + // long as you keep track of the length yourself! + // + // A "string" in Zig is a pointer to an array of const u8 values + // or a slice of const u8 values, into one, as we saw above). So, + // we could treat a "multi pointer" of const u8 a string as long + // as we can CONVERT IT TO A SLICE. (Hint: we do know the length!) + // + // Please fix this line so the print below statement can print it: + const zen12_string: []const u8 = zen_multiptr; + + // Here's the moment of truth! + std.debug.print("{s}\n", .{zen12_string}); +} +// +// Are all of these pointer types starting to get confusing? +// +// FREE ZIG POINTER CHEATSHEET! (Using u8 as the example type.) +// +---------------+----------------------------------------------+ +// | u8 | one u8 | +// | *u8 | pointer to one u8 | +// | [2]u8 | two u8s | +// | [*]u8 | pointer to unknown number of u8s | +// | [2]const u8 | two immutable u8s | +// | [*]const u8 | pointer to unknown number of immutable u8s | +// | *[2]u8 | pointer to an array of 2 u8s | +// | *const [2]u8 | pointer to an immutable array of 2 u8s | +// | []u8 | slice of u8s | +// | []const u8 | slice of immutable u8s | +// +---------------+----------------------------------------------+ |