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authorDave Gauer <dave@ratfactor.com>2021-03-07 10:08:07 -0500
committerDave Gauer <dave@ratfactor.com>2021-03-07 10:08:07 -0500
commit784b66ffcf8b26ec0b9699ab06ee46c14cbf886e (patch)
tree18d6d4b501e70770f490fcd93a99bd63583b7f5b /exercises/54_manypointers.zig
parent4a421cca28b8bd831dae3d6a22644c4c6932138c (diff)
"Multi pointers" are now "many pointers"
TypeInfo.Pointer.Size says "many", so there we are!
Diffstat (limited to 'exercises/54_manypointers.zig')
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diff --git a/exercises/54_manypointers.zig b/exercises/54_manypointers.zig
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+//
+// 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 "many pointer":
+ const zen_manyptr: [*]const u8 = zen12;
+
+ // It's okay to access zen_manyptr 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 "many 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_manyptr;
+
+ // 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 |
+// +---------------+----------------------------------------------+