C++ 11 feature: Initializer Lists and Static Assertions

In this chapter we shall study 2 new concepts of C++.

1. Initializer List
2. Static Assertions

1. Initializer List

It is used to initialize data members of a class or to create a container of elements.

It can be created using braced list syntax, for example {1, 2, 3}.

It will create a sequence of integers and will be of type std::initiaizer_list<int>.

Example:

int sum(const std::initializer_list<int>& list) {
  int total = 0;
  for (auto& e : list) {
    total += e;
  }

  return total;
}

auto list = {1, 2, 3};
sum(list); // == 6
sum({1, 2, 3}); // == 6
sum({}); // == 0

Static assertions are evaluated compile time.

It is used to check if the condition is true or false at the compile time.

Syntax:

static_assert( constant_expression, string_literal );

Prior to C++ 11 the only way to produce the compile time error messages is by using “#error” directive.

Example:

constexpr int x = 0;
constexpr int y = 1;
static_assert(x == y, "x != y");