Fixed-Size Heterogenous Collections

The C++ Utility library includes two class templates that can be used for storing multiple values of different types: std::pair and std::tuple. They are both collections with a fixed size. Like std::array, adding more values dynamically at runtime is impossible.

The big difference between std::pair and std::tuple is that std::pair can only hold two values, whereas std::tuple can be instantiated with an arbitrary size at compile time. We will begin with a brief introduction to std::pair before moving on to std::tuple.

Using std::pair

The class template std::pair lives in the <utility> header and has been available in C++ since the introduction of the standard template library. It is used in the standard library where algorithms need to return two values, such as std::minmax(), which can return both the smallest and the greatest value of an initializer list: