Within a constexpr or consteval function, we can use local variables that are not constexpr, and the value of these variables can be changed. As a silly example: #include<iostream>constevalintdoSomething(intx,i
constexpr does not guarantee compile-time evaluation; it just guarantees that the function can be evaluated at compile time for constant expression arguments if the programmer requires it or the compiler decides to do so to optimize. 常数表达式不会保证编译时计算;它只是表示如果函数的...
For example: template <class C> constexpr NL f6(C c) { // OK, the constexpr specifier ignored return NL(); } void g() { f6(55); // OK, not used in a constant expression } A call to a constexpr function produces the same result as a call to an equivalent non-constexpr ...
Enforcement(实施建议) Impossible and unnecessary. The compiler gives an error if a non-constexprfunction is called where a constant is required. 不可能也不必要。如果需要一个常量结果而非constexpr函数被调用的话,编译器会报错。 到此,关于“C++怎么定义constexpr”的学习就结束了,希望能够解决大家的疑惑。
When a function call is evaluated at compile-time, the compiler will calculate the return value of the function call at compile-time, and then replace the function call with the return value. So in our example, the call tocalcCircumference(3.0)is replaced with the result of the function cal...
The following example shows constexpr variables, functions, and a user-defined type. In the last statement in main(), the constexpr member function GetValue() is a run-time call because the value isn't required to be known at compile time....
The following example shows constexpr variables, functions, and a user-defined type. In the last statement in main(), the constexpr member function GetValue() is a run-time call because the value isn't required to be known at compile time....
Example The following example showsconstexprvariables, functions, and a user-defined type. In the last statement inmain(), theconstexprmember functionGetValue()is a run-time call because the value isn't required to be known at compile time. ...
(e.g., an array length or a nontype template argument), the compiler will attempt to evaluate a call to a constexpr function at compile time and issue an error if that is not possible (since a constant must be produced in the end). In other contexts, the compiler may or may not ...
(e.g., an array length or a nontype template argument), the compiler will attempt to evaluate a call to a constexpr function at compile time and issue an error if that is not possible (since a constant must be produced in the end). In other contexts, the compiler may or may not ...