Why constexpr is not working for const data member

Question

Hi

Refer code below:

Trying ro create a functor and constructor as constexpr

Whats wrong in this ? Does "const variable !=0" a const expression ?
https://code.sololearn.com/cshO4CMzMYk0/?ref=app

Answer 1

No, deno is a const value in the ctor context but it can be any value.
Futhermore static_assert is for compile-time assertions then the condition has to be compile-time avaible expression .

Think it like a preprocessor macro

Answer 2

It seems static_assert is for template only... at max, it works for local scoped variable , but not for argument. even const ref argument is also not working

void check(const int& b)
{
const int a = 3;

static_assert(a!=0,"not zero");
}

a will work on static assert , but b woll not

Answer 3

I belive ,

void check(const int& b)
{
const int a = 3;

static_assert(b!=0,"not zero");
}c

above should work if check is called with either

1.rvalue
check(5);

Or

2.Const int
const int a = 7;
check(a);