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Clarify the multidimensional array example

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Use a rectangular matrix instead of a square one to distinguish rows and
columns more clearly. Extend the example with row access.
This commit is contained in:
Andrew Barchuk 2024-10-05 17:36:54 +02:00 • committed by Alex Rønne Petersen
parent b350049f51
commit 5b4759bd3c
1 changed files with 13 additions and 9 deletions
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22
doc/langref/test_multidimensional_arrays.zig
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@ -1,18 +1,22 @@
const std = @import("std"); const std = @import("std");
const expect = std.testing.expect; const expect = std.testing.expect;
const expectEqual = std.testing.expectEqual;
const mat4x4 = [4][4]f32{ const mat4x5 = [4][5]f32{
[_]f32{ 1.0, 0.0, 0.0, 0.0 }, [_]f32{ 1.0, 0.0, 0.0, 0.0, 0.0 },
[_]f32{ 0.0, 1.0, 0.0, 1.0 }, [_]f32{ 0.0, 1.0, 0.0, 1.0, 0.0 },
[_]f32{ 0.0, 0.0, 1.0, 0.0 }, [_]f32{ 0.0, 0.0, 1.0, 0.0, 0.0 },
[_]f32{ 0.0, 0.0, 0.0, 1.0 }, [_]f32{ 0.0, 0.0, 0.0, 1.0, 9.9 },
}; };
test "multidimensional arrays" { test "multidimensional arrays" {
// mat4x5 itself is a one-dimensional array of arrays.
try expectEqual(mat4x5[1], [_]f32{ 0.0, 1.0, 0.0, 1.0, 0.0 });
// Access the 2D array by indexing the outer array, and then the inner array. // Access the 2D array by indexing the outer array, and then the inner array.
try expect(mat4x4[1][1] == 1.0); try expect(mat4x5[3][4] == 9.9);
// Here we iterate with for loops. // Here we iterate with for loops.
for (mat4x4, 0..) |row, row_index| { for (mat4x5, 0..) |row, row_index| {
for (row, 0..) |cell, column_index| { for (row, 0..) |cell, column_index| {
if (row_index == column_index) { if (row_index == column_index) {
try expect(cell == 1.0); try expect(cell == 1.0);
@ -20,8 +24,8 @@ test "multidimensional arrays" {
} }
} }
// initialize a multidimensional array to zeros // Initialize a multidimensional array to zeros.
const all_zero: [4][4]f32 = .{.{0} ** 4} ** 4; const all_zero: [4][5]f32 = .{.{0} ** 5} ** 4;
try expect(all_zero[0][0] == 0); try expect(all_zero[0][0] == 0);
} }