Just curious when is the ABSL_ASSERT? Can you explicitly tell me? Look at the error: absl/strings/string_view.h(501): error: constexpr function return is non-constant It says, in file absl/strings/string_view.h, in line 501, there is some error. When you look into that file, in...
提案P0595 希望加入一个新的 magic function 也就是 constexpr() 用来判断当前的函数是否在编译期执行,后来被更名为is_constant_evaluated并且进入 C++20。使用起来就像下面这样 constexpr int foo(int x) { if(std::is_constant_evaluated()) { return x; } else { return x + 1; } } 这样的话编译...
我在这里只是猜测，但可能是因为std::string s = "abc"是一个自动变量，并在函数开始时在堆栈中分配...
示例代码如下: classPoint{public:constexprPoint(doublexVal,doubleyVal):x(xVal),y(yVal){}constexprdoublegetX()const{returnx;}constexprdoublegetY()const{returny;}private:doublex,y;};intmain(){constexprPointp(9.5,7.3);// 编译时创建Point对象static_assert(p.getX()==9.5,"X should be 9.5....
void function1() { x=100; // OK. } void function2() const { x=100; // ERROR. The const methods can't change the values of object fields. } }; 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. constexpr是一个不同的概念。如果将编译时常量作为参数传递,则它将一个函...
{returnN; }// Recursive constexpr functionconstexprintfac(intn){returnn ==1?1: n * fac(n -1); }// User-defined typeclassFoo{public:constexprexplicitFoo(inti): _i(i){}constexprintGetValue()const{return_i; }private:int_i; };intmain(){// foo is const:constexprFoofoo(5);//...
// Recursive constexpr function constexpr int fac(int n) { return n == 1 ? 1 : n*fac(n - 1); } // User-defined type class Foo { public: constexpr explicit Foo(int i) : _i(i) {} constexpr int GetValue() { return _i; ...
return true; if (TREE_THIS_VOLATILE (t)) { if (flags & tf_error) error ("expression %qE has side-effects", t); return false; } if (CONSTANT_CLASS_P (t)) return true; switch (TREE_CODE (t)) { case FUNCTION_DECL: case BASELINK: ...
Onereturnstatement When a nonstatic member function that is not a constructor is declared with theconstexprspecifier, that member function is constant, and theconstexprspecifier has no other effect on the function type. The class of which that function is a member must be a literal type. ...
Constexpr functions can be used in constant expressions Aconstexpr functionis a function that is allowed to be called in a constant expression. To make a function a constexpr function, we simply use theconstexprkeyword in front of the function’s return type. ...