66 lines
2.1 KiB
Zig
66 lines
2.1 KiB
Zig
//
|
|
// ------------------------------------------------------------
|
|
// TOP SECRET TOP SECRET TOP SECRET TOP SECRET TOP SECRET
|
|
// ------------------------------------------------------------
|
|
//
|
|
// Are you ready for the THE TRUTH about Zig string literals?
|
|
//
|
|
// Here it is:
|
|
//
|
|
// @TypeOf("foo") == *const [3:0]u8
|
|
//
|
|
// Which means a string literal is a "constant pointer to a
|
|
// zero-terminated (null-terminated) fixed-size array of u8".
|
|
//
|
|
// Now you know. You've earned it. Welcome to the secret club!
|
|
//
|
|
// ------------------------------------------------------------
|
|
//
|
|
// Why do we bother using a zero/null sentinel to terminate
|
|
// strings in Zig when we already have a known length?
|
|
//
|
|
// Versatility! Zig strings are compatible with C strings (which
|
|
// are null-terminated) AND can be coerced to a variety of other
|
|
// Zig types:
|
|
//
|
|
// const a: [5]u8 = "array".*;
|
|
// const b: *const [16]u8 = "pointer to array";
|
|
// const c: []const u8 = "slice";
|
|
// const d: [:0]const u8 = "slice with sentinel";
|
|
// const e: [*:0]const u8 = "many-item pointer with sentinel";
|
|
// const f: [*]const u8 = "many-item pointer";
|
|
//
|
|
// All but 'f' may be printed. (A many-item pointer without a
|
|
// sentinel is not safe to print because we don't know where it
|
|
// ends!)
|
|
//
|
|
const print = @import("std").debug.print;
|
|
|
|
const WeirdContainer = struct {
|
|
data: [*]const u8,
|
|
length: usize,
|
|
};
|
|
|
|
pub fn main() void {
|
|
// WeirdContainer is an awkward way to house a string.
|
|
//
|
|
// Being a many-item pointer (with no sentinel termination),
|
|
// the 'data' field "loses" the length information AND the
|
|
// sentinel termination of the string literal "Weird Data!".
|
|
//
|
|
// Luckily, the 'length' field makes it possible to still
|
|
// work with this value.
|
|
const foo = WeirdContainer{
|
|
.data = "Weird Data!",
|
|
.length = 11,
|
|
};
|
|
|
|
// How do we get a printable value from 'foo'? One way is to
|
|
// turn it into something with a known length. We do have a
|
|
// length... You've actually solved this problem before!
|
|
//
|
|
// Here's a big hint: do you remember how to take a slice?
|
|
const printable = ???;
|
|
|
|
print("{s}\n", .{printable});
|
|
}
|