CPP Cheat Sheet 2026

The 30 highest-yield CPP facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. How should CPP professionals measure success in performance optimization & profiling? → Using defined metrics, benchmarks, and regular evaluation against established goals
2. Which STL container provides constant-time access by index and automatic resizing? → std::vector
3. What is the key difference between composition and inheritance as design strategies? → Composition models a 'has-a' relationship; inheritance models an 'is-a' relationship
4. What does write() return when it encounters an error? → -1
5. Which of the following statements about std::array is TRUE? → Its size is fixed at compile time and it is stack-allocated by default
6. Which method of std::map returns an iterator to an element if found, or end() if not? → find()
7. What is the conventional return type for the copy assignment operator (operator=)? → T&
8. Which SOLID principle does the Open/Closed Principle (OCP) describe? → Software entities should be open for extension but closed for modification
9. What does the '*' operator do when used with pointers? → Returns the value stored at the memory address
10. What is the result of the fold expression `(args + ...)` when args is an empty pack? → Compilation error for operator+
11. What does the RAII idiom guarantee in C++ memory management? → Resources are acquired in a constructor and released in the corresponding destructor
12. What happens when you delete a pointer that was not allocated with new? → It is undefined behavior
13. What does the 'explicit' keyword do when applied to a constructor? → Prevents the constructor from being used for implicit type conversions
14. Which algorithm computes the sum of a range sequentially from left to right? → std::accumulate
15. What happens when an exception is thrown inside a destructor that is already executing due to stack unwinding? → std::terminate() is called
16. What does the ThreadSanitizer (TSan) detect in C++ multithreaded applications? → Data races where two threads access shared memory without synchronization
17. Which of the following is NOT a valid use of catch(...)? → Accessing the caught exception object's members
18. What does the C++17 structured binding `auto [x, y] = std::make_pair(1, 2.0);` deduce for `x` and `y`? → x is int, y is double
19. What is the relationship between unit testing & code quality and overall C++ Programming Professional Certificate professional competency? → It is an essential component that strengthens the overall competency framework
20. What does 'false sharing' mean in the context of multi-threaded performance? → Threads access different variables that reside on the same cache line
21. What is the relationship between templates & generic programming and overall C++ Programming Professional Certificate professional competency? → It is an essential component that strengthens the overall competency framework
22. What is the purpose of `std::enable_if` in template programming? → To conditionally enable a template specialization based on a compile-time boolean
23. What is the purpose of std::allocator in C++? → To provide a customizable memory allocation strategy for containers
24. Which sorting algorithm does std::stable_sort typically use? → Merge sort
25. Which file stream method returns the current position of the get pointer? → tellg()
26. Which cache concept refers to the tendency of programs to access memory locations near recently accessed locations? → Spatial locality
27. What is the relationship between concurrency & multithreading and overall C++ Programming Professional Certificate professional competency? → It is an essential component that strengthens the overall competency framework
28. What is the effect of declaring a move constructor as noexcept on container operations like std::vector resize? → The vector will use the move constructor instead of copy constructor during reallocation
29. What is the relationship between build systems & package management and overall C++ Programming Professional Certificate professional competency? → It is an essential component that strengthens the overall competency framework
30. What does `make -j$(nproc)` accomplish on a Linux system? → Launches parallel make jobs up to the number of available CPU cores