Is it possible to print a variable's type in standard C++?

Question

For example:

int a = 12;
cout << typeof(a) << endl;

Expected output:

int

Answer 1

As explained by Scott Meyers in Effective Modern C++,

Calls to std::type_info::name are not guaranteed to return anythong sensible.

The best solution is to let the compiler generate an error message during the type deduction, for example,

template
class TD;

int main(){
    const int theAnswer = 32;
    auto x = theAnswer;
    auto y = &theAnswer;
    TD xType;
    TD yType;
    return 0;
}

The result will be something like this, depending on the compilers,

test4.cpp:10:21: error: aggregate ‘TD xType’ has incomplete type and cannot be defined TD xType;

test4.cpp:11:21: error: aggregate ‘TD yType’ has incomplete type and cannot be defined TD yType;

Hence, we get to know that x's type is int, y's type is const int*