const int array_size1 (int x) { return x+1; } // Error, constant expression required in array declaration int array[array_size1(10)]; constexpr int array_size2 (int x) { return x+1; } // OK, constexpr functions can be evaluated at compile time // and used in contexts that r...
s0is a constant, but it does not promise to be initialized at compile-time.s1is markedconstexpr, so it is a constant and, becauseS's constructor is also markedconstexpr, it will be initialized at compile-time. Mostly this matters when initialization at runtime would be time-consuming and ...
constexpr std::array<int, N1+N2> concat(const std::array<int, N1>& a1, const std::array<int, N2>& a2){ return std::array<int,N1+N2>{a1[0],a1[1],a1[2],a2[0],a2[1]}; } (注意aggregate-initialization从一系列整数值初始化对象) 显然,手动硬编码对两个数组的值的所有索引访问并不...
designated initialization new (p) T{.x = 1, .y = 2} // placement new version // construct_at version cannot exist 提案P2747R1 希望在常量求值中直接支持placement new。暂时还未被加入标准。 2024-∞:未来无极限! 截止目前,C++ 的常量求值已经支持了非常丰富的功能,支持条件,变量,循环,虚函数调用...
If the initialization is performed by a constructor, the constructor must be declared as constexpr. A reference may be declared as constexpr when both these conditions are met: The referenced object is initialized by a constant expression, and any implicit conversions invoked during initialization ...
A reference may be declared asconstexprwhen both these conditions are met: The referenced object is initialized by a constant expression, and any implicit conversions invoked during initialization are also constant expressions. All declarations of aconstexprvariable or function must have theconstexprspec...
constinitforces constant initialization of static or thread-local variables. It can help to limit static order initialization fiasco by using precompiled values and well-defined order rather than dynamic initialization and linking order… #include<array>// init at compile timeconstexprintcompute(intv)...
If the initialization is performed by a constructor, the constructor must be declared as constexpr. A reference may be declared as constexpr when both these conditions are met: The referenced object is initialized by a constant expression, and any implicit conversions invoked during initialization ...
[severity:I’m unable to use this version] Hi, I am writing today to report a crash that happens when cl compiles a heavily templated constexpr initialization of a std::array. Compiler version: Microsoft (R) C/C++ Optimizing Compiler Version...
Theconstexprfunction is executed in a context evaluated at compile time. This can be astatic_assertexpression, such as with the type-traits library or the initialization of a C-array. The value of aconstexprfunction is requested withconstexpr:constexpr auto res = func(5); ...