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A constexpr variable must be initialized at compile time. All constexpr variables are const . A variable can be declared with constexpr , when it has a literal type and is initialized. If the initialization is performed by a constructor, the constructor must be declared as constexpr .
In C++11, constexpr member functions are implicitly const.
const can only be used with non-static member function whereas constexpr can be used with member and non-member functions, even with constructors but with condition that argument and return type must be of literal types.
A const int var can be dynamically set to a value at runtime and once it is set to that value, it can no longer be changed. A constexpr int var cannot be dynamically set at runtime, but rather, at compile time. And once it is set to that value, it can no longer be changed.
For example:
constexpr int g() { return 30; }
constexpr int f()
{
// Can we omit const?
const int x = g();
const int y = 10;
return x + y;
}
Is there any point to ever declare local variables in a constexpr function with const?
Aren't constexpr functions with const local variables equivalent to those with no const?
In other words, does constexpr on a function impose (imply) const on its local variables?
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