How to Determine if a Type is an STL Container at Compile Time?

Determine if a Type is an STL Container at Compile Time

Determining if a given type is an STL container at compile time is a common requirement in C programming. To achieve this, we can leverage template metaprogramming techniques.

Proposed Solution

The following class template checks if a type meets specific criteria for STL containers:

template<typename T>
struct is_container : std::integral_constant<bool,
  has_const_iterator<T>::value &&
  has_begin_end<T>::beg_value &&
  has_begin_end<T>::end_value>
{ };

How it Works

This class template relies on a few helper templates:

• has_const_iterator checks if a type has a const_iterator type.
• has_begin_end checks if a type has begin and end member functions. For containers, these functions return iterators.

Usage

We can use the is_container template as follows:

std::cout << is_container<std::vector<int>>::value << std::endl; // Outputs "true"
std::cout << is_container<std::list<int>>::value << std::endl; // Outputs "true"
std::cout << is_container<std::map<int>>::value << std::endl; // Outputs "true"
std::cout << is_container<std::set<int>>::value << std::endl; // Outputs "true"
std::cout << is_container<int>::value << std::endl; // Outputs "false"

This approach allows us to determine if a type qualifies as an STL container at compile time, ensuring robust and efficient code.

The above is the detailed content of How to Determine if a Type is an STL Container at Compile Time?. For more information, please follow other related articles on the PHP Chinese website!