1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// <array>
10
11// reference front(); // constexpr in C++17
12// reference back(); // constexpr in C++17
13
14#include <array>
15#include <cassert>
16
17#include "test_macros.h"
18
19TEST_CONSTEXPR_CXX17 bool tests() {
20 {
21 typedef double T;
22 typedef std::array<T, 3> C;
23 C c = {1, 2, 3.5};
24
25 C::reference r1 = c.front();
26 assert(r1 == 1);
27 r1 = 5.5;
28 assert(c[0] == 5.5);
29
30 C::reference r2 = c.back();
31 assert(r2 == 3.5);
32 r2 = 7.5;
33 assert(c[2] == 7.5);
34 }
35 {
36 typedef double T;
37 typedef std::array<T, 0> C;
38 C c = {};
39 ASSERT_SAME_TYPE(decltype(c.back()), C::reference);
40 LIBCPP_ASSERT_NOEXCEPT(c.back());
41 ASSERT_SAME_TYPE(decltype(c.front()), C::reference);
42 LIBCPP_ASSERT_NOEXCEPT(c.front());
43 if (c.size() > (0)) { // always false
44 TEST_IGNORE_NODISCARD c.front();
45 TEST_IGNORE_NODISCARD c.back();
46 }
47 }
48 {
49 typedef double T;
50 typedef std::array<const T, 0> C;
51 C c = {};
52 ASSERT_SAME_TYPE(decltype(c.back()), C::reference);
53 LIBCPP_ASSERT_NOEXCEPT(c.back());
54 ASSERT_SAME_TYPE(decltype(c.front()), C::reference);
55 LIBCPP_ASSERT_NOEXCEPT(c.front());
56 if (c.size() > (0)) {
57 TEST_IGNORE_NODISCARD c.front();
58 TEST_IGNORE_NODISCARD c.back();
59 }
60 }
61
62 return true;
63}
64
65int main(int, char**) {
66 tests();
67#if TEST_STD_VER >= 17
68 static_assert(tests(), "");
69#endif
70 return 0;
71}
72

source code of libcxx/test/std/containers/sequences/array/front_back.pass.cpp