Logical C++

logical_cpp.cpp

// alignas C++11, C++14

class alignas(32) Foo {...}

// address &foo is aligned to 32-byes boundary
Foo foo{};

// it is not guarantee that address pFoo is aligned to 32-byes boundary
Foo* pFoo = new Foo();

// there is no standard way to align heap-allocated addresses to a specific boundary in C++11 and C++14
// you can use C11 function aligned_alloc but C11 is not part of C++11/14 standards and therefore it is not portable

//////////////////////////////////////////////////////////////////////
// if constexpr in C++17

// the code below does not compile, because if constexpt instantiates code not dependent on template parameters even in else branch 

#include <iostream>

template <typename T>
void test_print(T t)
{
    if constexpr (std::is_integral_v<T>)
    {
        static_assert(sizeof(int)==1, "Hello from C++17");
    }
    
    std::cout << t << std::endl;
};

int main()
{
   test_print(std::string("Hello World"));
}

// the code blow compiles necause static_assert depends on the template parameter T so the former one is eliminated

#include <iostream>

template <typename T>
void test_print(T t)
{
    if constexpr (std::is_integral_v<T>)
    {
        static_assert(sizeof(T)==1, "Hello from C++17");
    }
    
    std::cout << t << std::endl;
};

int main()
{
   test_print(std::string("Hello World"));
}