How Can I Create Heterogeneous Containers in C ?

Heterogeneous Containers in C

The graphic you referenced illustrates various STL containers based on characteristics such as fixed/variable size, data type, sorting, and access type. However, it lacks a container that simultaneously supports variable size and heterogeneity (accommodating different data types).

In C , most containers are designed to hold objects of a specific type using templates. While pointers can allow for heterogenous storage, they pose limitations. Additionally, void* containers are less type-safe.

For true heterogeneous containers that can store unrelated types, consider the following options:

• Boost.Any:

  Boost.Any provides a general way to store any type, allowing you to create containers that hold a mix of integers, strings, and even more complex objects.

  <code class="cpp">using boost::any;
  std::list<boost::any> values;
  values.push_back(42);
  values.push_back("Hello, world!");</code>

• Boost.Variant:

  Boost.Variant is similar to Boost.Any but requires specifying the allowed types at compile time. This enforces type safety while still enabling heterogeneous storage.

  <code class="cpp">using boost::variant;
  std::vector<boost::variant<int, std::string>> vec;
  vec.push_back(44);
  vec.push_back("C++");</code>

These libraries allow for the creation of containers that can flexibly store and access data of various types. While not directly provided by the STL, these alternatives offer solutions for heterogeneous data storage in C .

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