55 lines
2.4 KiB
Zig
55 lines
2.4 KiB
Zig
//
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// You can also make pointers to multiple items without using a slice.
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//
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// var foo: [4]u8 = [4]u8{ 1, 2, 3, 4 };
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// var foo_slice: []u8 = foo[0..];
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// var foo_ptr: [*]u8 = &foo;
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//
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// The difference between foo_slice and foo_ptr is that the slice has
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// a known length. The pointer doesn't. It is up to YOU to keep track
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// of the number of u8s foo_ptr points to!
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//
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const std = @import("std");
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pub fn main() void {
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// Take a good look at the array type to which we're coercing
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// the zen12 string (the REAL nature of strings will be
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// revealed when we've learned some additional features):
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const zen12: *const [21]u8 = "Memory is a resource.";
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//
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// It would also have been valid to coerce to a slice:
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// const zen12: []const u8 = "...";
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//
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// Now let's turn this into a "many-item pointer":
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const zen_manyptr: [*]const u8 = zen12;
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// It's okay to access zen_manyptr just like an array or slice as
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// long as you keep track of the length yourself!
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//
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// A "string" in Zig is a pointer to an array of const u8 values
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// (or a slice of const u8 values, as we saw above). So, we could
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// treat a "many-item pointer" of const u8 as a string as long as
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// we can CONVERT IT TO A SLICE. (Hint: we do know the length!)
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//
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// Please fix this line so the print statement below can print it:
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const zen12_string: []const u8 = zen_manyptr[0..21];
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// Here's the moment of truth!
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std.debug.print("{s}\n", .{zen12_string});
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}
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//
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// Are all of these pointer types starting to get confusing?
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//
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// FREE ZIG POINTER CHEATSHEET! (Using u8 as the example type.)
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// +---------------+----------------------------------------------+
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// | u8 | one u8 |
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// | *u8 | pointer to one u8 |
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// | [2]u8 | two u8s |
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// | [*]u8 | pointer to unknown number of u8s |
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// | [*]const u8 | pointer to unknown number of immutable u8s |
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// | *[2]u8 | pointer to an array of 2 u8s |
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// | *const [2]u8 | pointer to an immutable array of 2 u8s |
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// | []u8 | slice of u8s |
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// | []const u8 | slice of immutable u8s |
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// +---------------+----------------------------------------------+
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