C++11, C++14, C++17, and C++20 Features Asked in Interviews

C++ has come a long way since its early days. With each new standard, the language has introduced features that improve performance, safety, readability, and developer productivity. For job seekers, these modern features are often central to cpp interview questions, especially for roles involving system-level programming, performance-critical applications, or modern C++ development.

In this blog, we’ll explore the most important C++11, C++14, C++17, and C++20 features that interviewers love to ask about, along with explanations and example use cases.

Why Interviewers Ask About Modern C++ Standards

• Relevance in Industry: Many companies still maintain legacy C++ code but expect developers to understand modern practices.

• Code Quality: Modern C++ features reduce boilerplate code and improve readability.

• Performance: Several improvements (move semantics, constexpr, concepts) directly impact runtime efficiency.

• Best Practices: Knowledge of smart pointers, threading libraries, and new syntactic sugar shows you write safer, cleaner code.

If you’re preparing for cpp interview questions, you must be able to compare standards, explain why new features were introduced, and provide examples.

C++11 Features Asked in Interviews

C++11 was a major upgrade and is often called C++0x done right.

Key Features to Know:

1. Auto Keyword

   • Allows type inference from initializer.

   • Interview Question: “What is the advantage of using auto in C++11?”

2. Range-based for Loops

   • Simplifies iteration over containers.

   • Example:

     for (auto x : vec) { /*...*/ }

3. nullptr

   • Replaces old NULL macros with type-safe null pointer.

4. Move Semantics & Rvalue References

   • Improves performance by avoiding unnecessary deep copies.

   • Interviewers often ask: “Explain move constructor vs copy constructor.”

5. Smart Pointers (unique_ptr, shared_ptr, weak_ptr)

   • Replaces raw pointers for automatic memory management.

   • A very common cpp interview question is: “What’s the difference between unique_ptr and shared_ptr?”

6. Lambda Expressions

   • Anonymous functions introduced for inline usage.

   • Example:

     auto add = [](int a, int b) { return a + b; };

7. Thread Library

   • Built-in multithreading support with std::thread.

   • Interviewers may ask: “How do you create and join threads in C++11?”

8. constexpr

   • Compile-time constant evaluation.

Why Important in Interviews: Most cpp interview questions on C++11 revolve around memory management, move semantics, smart pointers, and lambda usage.

C++14 Features Asked in Interviews

C++14 was more of a refinement release to C++11.

Key Features to Know:

1. Binary Literals & Digit Separators

   • Example:

     int x = 0b1010; // binary literal int y = 1'000'000; // digit separator

2. Generic Lambdas

   • Lambdas can now have auto parameters.

   • Example:

     auto f = [](auto a, auto b) { return a + b; };

3. Return Type Deduction

   • Functions can deduce return types using auto.

4. make_unique

   • Complements unique_ptr, making memory allocation safer.

Why Important in Interviews: While C++14 is minor, interviewers may ask cpp interview questions like “What’s new in C++14 compared to C++11?” to test your awareness.

C++17 Features Asked in Interviews

C++17 brought significant enhancements that are very popular in modern coding interviews.

Key Features to Know:

1. Structured Bindings

   • Allows unpacking tuples/pairs.

   • Example:

     auto [key, value] = myMapEntry;

2. if with Initializers

   • Example:

     if (auto it = myMap.find(x); it != myMap.end()) { /* ... */ }

3. std::optional

   • Handles nullable values more safely than raw pointers.

4. std::variant

   • Type-safe union alternative.

5. std::any

   • Stores any type of data, checked at runtime.

6. Filesystem Library

   • New std::filesystem for file handling operations.

7. Parallel Algorithms in STL

   • Execute algorithms with multiple execution policies (parallel, sequential).

Why Important in Interviews: cpp interview questions from C++17 usually focus on optional, variant, any, structured bindings, and the filesystem library.

C++20 Features Asked in Interviews

C++20 is one of the most revolutionary updates since C++11. It introduces powerful features that interviewers increasingly ask about.

Key Features to Know:

1. Concepts

   • Constraints on template parameters.

   • Example:

     template<typename T> requires std::integral<T> T add(T a, T b) { return a + b; }

2. Ranges

   • Easier manipulation of collections using pipelines.

3. Coroutines

   • Functions that can suspend and resume (co_yield, co_return).

   • Interviewers may ask: “How do coroutines differ from threads in C++20?”

4. Modules

   • Replaces header files with more efficient module imports.

5. Three-way Comparison (Spaceship Operator <=>)

   • Simplifies comparisons.

6. constexpr Enhancements

   • More constructs can be evaluated at compile time.

7. Calendar and Time Zone Library

   • Provides standardized date/time handling.

Why Important in Interviews: C++20 is relatively new, so many cpp interview questions test whether candidates know about concepts, coroutines, ranges, and modules.

Common Interview Question Patterns

When companies ask about modern C++ features, the cpp interview questions often take these forms:

• What’s the difference between C++11 and earlier versions?

• Why do we need move semantics when we already have copy constructors?

• How do smart pointers improve memory management in C++11 and beyond?

• What are structured bindings in C++17 and how are they used?

• Explain concepts in C++20 with an example.

• What problem does std::optional solve compared to raw pointers or special values?

Tips to Answer These Questions

1. Explain the Problem First: Don’t just define the feature; explain what issue it solves.

2. Give a Code Example: Even short snippets show practical knowledge.

3. Compare with Previous Standard: Employers love to see that you understand the evolution of C++.

4. Mention Real-World Use Cases: Link features to applications like gaming engines, financial systems, or system software.

Final Thoughts

Modern C++ has evolved dramatically with C++11, C++14, C++17, and C++20, making it more powerful and expressive. For developers, being familiar with these features is essential not just for writing clean, efficient code but also for succeeding in technical interviews.

When preparing for cpp interview questions, focus on:

• C++11: Move semantics, smart pointers, lambdas, threads.

• C++14: Generic lambdas, make_unique, return type deduction.

• C++17: Structured bindings, optional, variant, filesystem.

• C++20: Concepts, ranges, coroutines, modules.

By understanding both the “what” and “why” behind these features, you’ll be ready to impress interviewers and show that you are well-versed in modern C++ practices.