C++11

Question 1

trailing return type

Answer 1

template
auto multiply(T lhs, S rhs) -> decltype(lhs * rhs) {
  return lhs * rhs;
}

Question 2

decltype

Answer 2

A keyword to query the type of an expression. It is typically to express types depending on template parameters.

Question 3

range-based “for” loop

Answer 3

int my_array [5] = {1, 2, 3, 4, 5};

for (auto& x : my_array ) { x *= 2; }

Question 4

lambda functions/expressions

Answer 4

-> int { return x + y; }

Question 5

expose base-class c’tors in a derived class

Answer 5

using BaseClass::BaseClass; // all of them

Question 6

override

Answer 6

The override special identifier means that the compiler will check the base class(es) to see if there is a virtual function with this exact signature. This is to prevent accidental creation of a new virtual function where an override was meant.

Question 7

final

Answer 7

virtual void f() final;

This prevents derived classes from overriding it or using the same method name in derived classes.

Question 8

nullptr type

Answer 8

nullptr_t, which is implicitly convertible and comparable with pointer types and bool.

Question 9

strongly typed enumerations

Answer 9

enum class E1: unsigned {Val1 = 1, Val2}; // unsigned is the underlying type for E1. However, elements of E1 cannot be directly compared to unsigned. Their scoping is also limited to E1 rather than the enclosing scope.

Question 10

variadic templates

Answer 10

Templates can take a variable number of parameters. Example:
template class tuple;

Question 11

template aliases

Answer 11

template
class SomeType ;
template
using TypedefName = SomeType ;

Question 12

tuples

Answer 12

typedef std::tuple  test_tuple;
long lengthy = 12;
test_tuple proof (18, 6.5, lengthy, "Ciao!");
lengthy = std::get<0>(proof);
std::get<3>(proof) = " Beautiful!";

Question 13

STL hash tables

Answer 13

unordered_{set, multiset, map, multimap}

Question 14

regex

Answer 14

regex_search, regex_replace, match_results

Question 15

smart pointers

Answer 15

unique_ptr, shared_ptr, weak_ptr.

Question 16

wrapper references

Answer 16

int i = 0;
g(func, i);
g(func, std::ref(i));

Question 17

initializer list constructor

Answer 17

std::vector x {4};
// vs. std::vector x (4);