In the C++ Standard Template Library (STL), what does a sequence adaptor such as std::stack or std::queue provide?

Introduction / Context:
The C++ Standard Template Library contains not only basic containers but also container adaptors, including sequence adaptors such as std::stack, std::queue and std::priority_queue. These adaptors sit on top of underlying sequence containers and change how you interact with them. This question asks what a sequence adaptor provides in terms of functionality and interface.

Given Data / Assumptions:

• We are considering sequence container adaptors like std::stack and std::queue.
• These adaptors are built on top of underlying sequence containers such as std::deque or std::vector.
• The main role of an adaptor is to change the interface presented to the user.

Concept / Approach:
A sequence adaptor reuses an existing container type to store elements but exposes only a limited set of operations that correspond to a specific abstract data type. For example, std::stack uses an underlying container and allows push, pop and top, but does not expose random access or iteration. Similarly, std::queue provides operations such as push, pop, front and back to model a first in first out queue. This design separates storage from interface and lets you choose the underlying container type through template parameters while using a simple adaptor interface at the call site.

Step-by-Step Solution:
Step 1: Recall that adaptors wrap existing containers and restrict or change the interface.Step 2: Recognise that std::stack and std::queue are examples of sequence adaptors that present stack like or queue like operations.Step 3: Option A states that a sequence adaptor provides an interface that adapts an underlying sequence container into a restricted view such as a stack or queue.Step 4: Options B, C, D and E describe memory management, code generation, associative containers or hardware drivers, none of which match the STL definition of a sequence adaptor.Step 5: Therefore, option A is the correct answer.

Verification / Alternative check:
Looking at the declaration of std::stack, you will see a template parameter for the underlying container, often defaulted to std::deque. The public interface of std::stack does not expose operations like insert at arbitrary positions, even though the underlying container might support them. Instead, it offers push, pop and top, which implement last in first out semantics. This is exactly what it means to adapt a sequence container to a stack interface.

Why Other Options Are Wrong:
Option B confuses sequence adaptors with low level memory allocators. Option C talks about generating source code at run time, which the STL does not do. Option D claims adaptors replace associative containers, but associative containers such as std::map are separate types with different interfaces. Option E refers to device drivers, which are outside the scope of container adaptors.

Common Pitfalls:
Developers sometimes assume that they can treat a sequence adaptor exactly like its underlying container and are surprised when operations such as iteration are not available. Another pitfall is forgetting that you can customise the underlying container when better performance or memory characteristics are needed. For exam purposes, remember that sequence adaptors provide a restricted interface that adapts an underlying sequence container to a specific abstract data type such as a stack or queue.

Final Answer:
An interface that adapts an underlying sequence container to provide a restricted view such as stack or queue behaviour.