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exercises(triangle): return an optional, not an error union #257

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exercises(triangle): return an optional, not an error union #257

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2 changes: 2 additions & 0 deletions config.json
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Original file line number Diff line number Diff line change
Expand Up @@ -264,6 +264,7 @@
"error-sets",
"functions",
"methods",
"optionals",
"structs"
],
"prerequisites": [
Expand All @@ -272,6 +273,7 @@
"error-sets",
"functions",
"methods",
"optionals",
"structs"
],
"difficulty": 1
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8 changes: 2 additions & 6 deletions exercises/practice/triangle/.meta/example.zig
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Original file line number Diff line number Diff line change
@@ -1,14 +1,10 @@
pub const TriangleError = error{
Invalid,
};

pub const Triangle = struct {
a: f64,
b: f64,
c: f64,

pub fn init(a: f64, b: f64, c: f64) TriangleError!Triangle {
if ((a + b <= c) or (a + c <= b) or (b + c <= a)) return TriangleError.Invalid;
pub fn init(a: f64, b: f64, c: f64) ?Triangle {
if ((a + b <= c) or (a + c <= b) or (b + c <= a)) return null;
return Triangle{ .a = a, .b = b, .c = c };
}

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74 changes: 37 additions & 37 deletions exercises/practice/triangle/test_triangle.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -4,106 +4,106 @@ const testing = std.testing;
const triangle = @import("triangle.zig");

test "equilateral all sides are equal" {
const actual = try triangle.Triangle.init(2, 2, 2);
try testing.expect(actual.isEquilateral());
const actual = triangle.Triangle.init(2, 2, 2);
try testing.expect(actual.?.isEquilateral());
}

test "equilateral any side is unequal" {
const actual = try triangle.Triangle.init(2, 3, 2);
try testing.expect(!actual.isEquilateral());
const actual = triangle.Triangle.init(2, 3, 2);
try testing.expect(!actual.?.isEquilateral());
}

test "equilateral no sides are equal" {
const actual = try triangle.Triangle.init(5, 4, 6);
try testing.expect(!actual.isEquilateral());
const actual = triangle.Triangle.init(5, 4, 6);
try testing.expect(!actual.?.isEquilateral());
}

test "equilateral all zero sides is not a triangle" {
const actual = triangle.Triangle.init(0, 0, 0);
try testing.expectError(triangle.TriangleError.Invalid, actual);
try testing.expect(actual == null);
}

test "equilateral sides may be floats" {
const actual = try triangle.Triangle.init(0.5, 0.5, 0.5);
try testing.expect(actual.isEquilateral());
const actual = triangle.Triangle.init(0.5, 0.5, 0.5);
try testing.expect(actual.?.isEquilateral());
}

test "isosceles last two sides are equal" {
const actual = try triangle.Triangle.init(3, 4, 4);
try testing.expect(actual.isIsosceles());
const actual = triangle.Triangle.init(3, 4, 4);
try testing.expect(actual.?.isIsosceles());
}

test "isosceles first two sides are equal" {
const actual = try triangle.Triangle.init(4, 4, 3);
try testing.expect(actual.isIsosceles());
const actual = triangle.Triangle.init(4, 4, 3);
try testing.expect(actual.?.isIsosceles());
}

test "isosceles first and last sides are equal" {
const actual = try triangle.Triangle.init(4, 3, 4);
try testing.expect(actual.isIsosceles());
const actual = triangle.Triangle.init(4, 3, 4);
try testing.expect(actual.?.isIsosceles());
}

test "equilateral triangles are also isosceles" {
const actual = try triangle.Triangle.init(4, 3, 4);
try testing.expect(actual.isIsosceles());
const actual = triangle.Triangle.init(4, 3, 4);
try testing.expect(actual.?.isIsosceles());
}

test "isosceles no sides are equal" {
const actual = try triangle.Triangle.init(2, 3, 4);
try testing.expect(!actual.isIsosceles());
const actual = triangle.Triangle.init(2, 3, 4);
try testing.expect(!actual.?.isIsosceles());
}

test "isosceles first triangle inequality violation" {
const actual = triangle.Triangle.init(1, 1, 3);
try testing.expectError(triangle.TriangleError.Invalid, actual);
try testing.expect(actual == null);
}

test "isosceles second triangle inequality violation" {
const actual = triangle.Triangle.init(1, 3, 1);
try testing.expectError(triangle.TriangleError.Invalid, actual);
try testing.expect(actual == null);
}

test "isosceles third triangle inequality violation" {
const actual = triangle.Triangle.init(3, 1, 1);
try testing.expectError(triangle.TriangleError.Invalid, actual);
try testing.expect(actual == null);
}

test "isosceles sides may be floats" {
const actual = try triangle.Triangle.init(0.5, 0.4, 0.5);
try testing.expect(actual.isIsosceles());
const actual = triangle.Triangle.init(0.5, 0.4, 0.5);
try testing.expect(actual.?.isIsosceles());
}

test "scalene no sides are equal" {
const actual = try triangle.Triangle.init(5, 4, 6);
try testing.expect(actual.isScalene());
const actual = triangle.Triangle.init(5, 4, 6);
try testing.expect(actual.?.isScalene());
}

test "scalene all sides are equal" {
const actual = try triangle.Triangle.init(4, 4, 4);
try testing.expect(!actual.isScalene());
const actual = triangle.Triangle.init(4, 4, 4);
try testing.expect(!actual.?.isScalene());
}

test "scalene first and second sides are equal" {
const actual = try triangle.Triangle.init(4, 4, 3);
try testing.expect(!actual.isScalene());
const actual = triangle.Triangle.init(4, 4, 3);
try testing.expect(!actual.?.isScalene());
}

test "scalene first and third sides are equal" {
const actual = try triangle.Triangle.init(3, 4, 3);
try testing.expect(!actual.isScalene());
const actual = triangle.Triangle.init(3, 4, 3);
try testing.expect(!actual.?.isScalene());
}

test "scalene second and third sides are equal" {
const actual = try triangle.Triangle.init(4, 3, 3);
try testing.expect(!actual.isScalene());
const actual = triangle.Triangle.init(4, 3, 3);
try testing.expect(!actual.?.isScalene());
}

test "scalene may not violate triangle inequality" {
const actual = triangle.Triangle.init(7, 3, 2);
try testing.expectError(triangle.TriangleError.Invalid, actual);
try testing.expect(actual == null);
}

test "scalene sides may be floats" {
const actual = try triangle.Triangle.init(0.5, 0.4, 0.6);
try testing.expect(actual.isScalene());
const actual = triangle.Triangle.init(0.5, 0.4, 0.6);
try testing.expect(actual.?.isScalene());
}
2 changes: 1 addition & 1 deletion exercises/practice/triangle/triangle.zig
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
pub const Triangle = struct {
// This struct, as well as its fields and methods, needs to be implemented.

pub fn init(a: f64, b: f64, c: f64) TriangleError!Triangle {
pub fn init(a: f64, b: f64, c: f64) ?Triangle {
_ = a;
_ = b;
_ = c;
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