[348] - Did you know that C++26 added more constexpr for <cmath> an…

…d `<complex>`?

README.md

@@ -12,6 +12,7 @@
 
 ### Tips
 
+* [[347]](/tips/347.md) - Did you know that C++26 added more constexpr for `<cmath>` and `<complex>`?
 * [[346]](/tips/346.md) - Did you know that C++26 added testing for success or failure of `<charconv>` functions?
 * [[345]](/tips/345.md) - Did you know that C++26 allows constexpr cast from `void*`?
 * [[344]](/tips/344.md) - Did you know that C++26 added `Member visit`?

tips/347.md

@@ -0,0 +1,62 @@
+<details open><summary>Info</summary><p>
+
+* **Did you know that C++26 added testing for success or failure of <charconv> functions?**
+
+ * https://wg21.link/P2497
+
+</p></details><details open><summary>Example</summary><p>
+
+```cpp
+constexpr std::to_chars_result result{{}};
+static_assert(result);
+```
+
+> https://godbolt.org/z/q16djPn3P
+
+</p></details><details open><summary>Puzzle</summary><p>
+
+* **Can you implement `format` fn which optionally converts given value to chars?**
+
+```cpp
+template <auto N>
+constexpr auto format(const auto value) -> std::optional<std::array<char, N>>; // TODO
+
+constexpr auto fmt_0 = format<1>(0);
+static_assert(fmt_0 and std::string_view{fmt_0->cbegin(), fmt_0->cend()} == std::string_view{"0"});
+
+constexpr auto fmt_42 = format<2>(42);
+static_assert(fmt_42 and std::string_view{fmt_42->cbegin(), fmt_42->cend()} == std::string_view{"42"});
+```
+
+> https://godbolt.org/z/rf7rWc3ee
+
+</p></details>
+
+</p></details><details><summary>Solutions</summary><p>
+
+```cpp
+template <auto N>
+constexpr auto format(const auto value) -> std::optional<std::array<char, N>> {
+ std::array<char, N> buffer;
+ return std::to_chars(buffer.begin(), buffer.end(), value)
+ ? std::optional(buffer)
+ : std::nullopt;
+}
+```
+
+> https://godbolt.org/z/c8vWbGKWf
+
+```cpp
+template <auto N>
+constexpr auto format(const auto value) -> std::optional<std::array<char, N>> {
+ std::array<char, N> result{};
+ if (not std::to_chars(result.begin(), result.end(), value)) {
+ return std::nullopt;
+ }
+ return result;
+}
+```
+
+> https://godbolt.org/z/nrWcq4rz5
+
+</p></details>

tips/348.md

@@ -0,0 +1,37 @@
+<details open><summary>Info</summary><p>
+
+*** **Did you know that C++26 added more constexpr for <cmath> and <complex>?**
+
+ * https://wg21.link/P1383
+
+</p></details><details open><summary>Example</summary><p>
+
+```cpp
+#include <cmath>
+constexpr auto positive = std::abs(-2);
+static_assert(positive == 2);
+```
+
+> https://godbolt.org/z/ar1drdohP
+
+</p></details><details open><summary>Puzzle</summary><p>
+
+* **Can you implement `number` user defined literal (UDL) which uses constexpr <cmath> functions?**
+
+```cpp
+#include <cmath>
+
+template <char... Cs>
+[[nodiscard]] constexpr auto operator""_number(); // TODO
+
+static_assert(0 == 0_number);
+static_assert(42 == 42_number);
+static_assert(123 == 123_number);
+```
+
+> https://godbolt.org/z/8r4frajnv
+
+</p></details>
+
+</p></details><details><summary>Solutions</summary><p>
+</p></details>