C++ Performance Quiz

How well do you know what the compiler does? Pick a question and find out.

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• Memory Layout: Array of Structs vs Struct of Arrays

  2 snippets

• Atomic Increment Ordering: relaxed vs. seq_cst

  2 snippets

• Atomic Store Ordering: memory_order_release vs memory_order_seq_cst

  2 snippets

• Lambda Capture: Value Capture vs Reference Capture

  2 snippets

• Sorted Array Search: std::lower_bound vs. Linear Scan

  2 snippets

• Power-of-Two Indexing: Bitwise AND vs operator%

  2 snippets

• Conditional Write: Two Control-Flow Styles

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• Lookup Table: Static Array vs. Stack Array

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• Integer Division: Compile-Time Constant vs. Runtime Variable

  2 snippets

• std::vector Insertion: emplace_back vs push_back

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• Removing Elements from a Vector: Two Approaches

  2 snippets

• Cache Coherency: Packed vs Padded Thread Counters

  2 snippets

• Free Function vs. Member Function

  2 snippets

• Read-Heavy Map Lookup: unordered_map vs. Sorted Vector + Binary Search

  2 snippets

• Struct Layout: Combined vs Split Field Storage

  2 snippets

• Container Iteration: std::list vs std::vector

  2 snippets

• std::list Traversal: Forward vs Two-Ended

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• Character Lower-casing: Locale-aware vs Lookup Table

  2 snippets

• Loop-Carried Dependency: Single vs Split Accumulator

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• Shared Pointer Creation: new vs make_shared

  2 snippets

• Map Lookup: find() vs. count() + at()

  2 snippets

• Key Lookup: std::map vs std::unordered_map

  2 snippets

• 2D Array Traversal: Row-Major vs Column-Major

  2 snippets

• Thread-Safe Counter: Two Synchronization Approaches

  2 snippets

• std::vector Reallocation: noexcept Move Constructor

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• Returning a Named Local: Plain Return vs std::move Return

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• Returning std::optional<Result>: Wrapper Local vs Value Local

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• Range-based for loop: copy vs reference

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• std::regex: Function-Local vs. Static-Local Declaration

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• std::vector Growth: reserve Before push_back vs Without

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• std::vector Pre-allocation: reserve vs resize

  2 snippets

• shared_ptr in a Loop: Copy per Iteration vs. Reuse Handle

  2 snippets

• Smart Pointer Move: shared_ptr Copy vs. unique_ptr Move

  2 snippets

• std::string: Short String Optimisation Buffer

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• std::sort Comparator: Function Pointer vs Lambda

  2 snippets

• Branch Prediction: Sorted vs. Shuffled Data

  2 snippets

• Buffer Allocation: Heap Buffer vs Stack Buffer

  2 snippets

• Buffer Zero-Initialization: std::fill vs. memset

  2 snippets

• Callback Dispatch: std::function vs Template Parameter

  2 snippets

• Copy vs Move Semantics: std::string Performance

  2 snippets

• Integer-to-String Conversion: std::to_string vs std::to_chars

  2 snippets

• String Building: Two Concatenation Styles

  2 snippets

• Substring Extraction: Owning String vs String View

  2 snippets

• Copying a Short String into a Large Buffer: strncpy vs memcpy

  2 snippets

• Dense Integer Dispatch: switch vs. Function-Pointer Table

  2 snippets

• Uncontended Mutex Guard: Inside vs. Outside the Loop Body

  2 snippets

• UTF-8 Code Point Counting: Nibble Table vs Range Checks

  2 snippets

• Removing a Vector Element: Stable vs Swap Removal

  2 snippets

• Element Storage: Pointer-Owned vs Value-Owned Elements

  2 snippets

• Polymorphic Dispatch: Virtual Function vs CRTP

  2 snippets

• Large Stack Buffer: Zero-Initialized vs Uninitialized

  2 snippets