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Comments on How do I (compactly) initialize a 2-d array of structs with the same value?

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How do I (compactly) initialize a 2-d array of structs with the same value?

−0

I learned about the ** operator for array-repeat, and I love it.

I have a struct that contains a 2-d array of inner structs, like

const D1 = 30;
const D2 = 40;
const Inner = struct { .a: u32, .b: bool };

const Outer = struct {
    // ...
    .array: [D1][D2]Inner,
    // ...
};

I would like to "just initialize" the struct in the init() function:

pub fn init() Self {
    return Self{
        .array = FIXME("What goes here?"),
    };
}

For a 1-d array, I could do something like:

// See line 63 of 
// https://ziglang.org/documentation/master/#Arrays

.array_1d = [_]Inner{.a='1', .b=true} ** D2,

But how do I write the expression for a 2-d array?

.array = [_][_]Inner{...} ** D2 ** D1,  // didn't work

array initialization zig

posted over 1 year ago

CC BY-SA 4.0

aghast‭

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1 comment thread

I don't do zig, but (1 comment)

Moshi‭ wrote over 1 year ago

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Does this work?

.{ .{ Inner{.a = '1', .b = true} } ** D2 } ** D1

Seems to work fine, but bear in mind that I don't use zig

By the way, I got some compilation errors where I'm not sure what I'm doing wrong: const Inner = struct { .a: u32, .b: bool }; (error: expected test, comptime, var decl, or container field, found '.') and [_]Inner{.a='1', .b=true} (error: initializing array with struct syntax).

This is my full code

const D1 = 30;
const D2 = 40;
const Inner = struct { a: u32, b: bool };

const Outer = struct {
    array: [D1][D2]Inner,

    pub fn init() Outer {
        return Outer {
            .array = .{ .{ Inner{.a = '1', .b = true} } ** D2 } ** D1,
        };
    }
};

test "basic test" {
    const outer = Outer.init();

    try std.testing.expectEqual(outer.array[5][5], Inner { .a = '1', .b = true});
}