core_language.md

Core language

Table of contents

• Introduction and overview
  • Abstract machine
• ABI and implementation
  • Itanium C++ ABI
  • Calling conventions
  • Implementation of inheritance
  • Implementation of exceptions
• Keywords
• Attributes
  • [[maybe_unused]]
  • [[likely]] / [[unlikely]]
  • [[nodiscard]]
  • [[noreturn]]
  • [[trivially_relocatable]]
• Declarations
  • alignas and alignment
  • auto
  • const and mutable
  • constexpr
    • constexpr and dynamic allocations
  • consteval
  • decltype and std::declval()
  • enum, enum class
  • friend
    • Friend function templates
    • Hidden friends
  • inline
  • static
  • static_assert
  • using
    • using enum
  • Elaborated type specifier
  • Flexible array member
  • Most vexing parse
  • Namespaces
  • Storage class specifiers
  • Structured binding
• Initialization
  • Aggregate initialization
  • Uniform initialization
  • constinit
• Dynamic memory
  • Alignment
  • Object creation and placement new
  • Global replacement of operator new and operator delete
• Exceptions
  • noexcept specifier
• Expressions
  • nullptr
  • Compound literals
  • User-defined literals
  • Operator precedence and associativity
  • Order of evaluation
  • Type conversions
    • dynamic_cast
  • Type punning
  • Value categories
• Flow control
  • Range-based for loop
  • if
    • if constexpr
  • switch
• Functions and function objects
  • Overload resolution
  • Argument-dependent lookup
  • Function wrappers
    • std::function
  • Lambda expressions
  • Member functions
    • Member function poiners
    • Special member functions
    • Explicit object parameter / deducing this
  • Deleted functions (= delete;)
  • main()
• Operators
  • Comparisons
    • Three-ways comparisons
    • Pointer comparisons
  • Conditional operator ?:
  • Logical operators
    • Implication
  • sizeof / alignof
• Types
  • void
  • Integral types
    • Integral promotion
    • wchar_t
  • Floating-point types
    • __float128
  • Trivial and POD types
  • Pointer and array types
    • Null pointers
  • Class types
    • Destructors
    • Layout
    • Member functions
    • Polymorphism and inheritance
  • Union types
  • Function types
  • References
    • Lifetime of a temporary
    • Rvalue references, universal references, and move semantics
  • Opaque typedefs
• Standards
  • C++11
  • C++14
  • C++17
  • C++20
• Tricks and subtleties
  • Accessing private and protected members
  • Embedding binary data
• C, C vs C++
  • Arrays
  • Functions
  • Static variables
  • Conditional operator

---

Introduction and overview

🔗

• K.Henney. C++ – an invisible foundation of everything – Overload 161 (2021)

❔

• The definitive C++ book guide and list – Stack Overflow

🎥

• W.E.Brown. What I think when I think about C++ – Core C++ (2022)
• V.Ciura. C++ mythbusters – Meeting C++ (2022)
• H.Sutter. Quantifying accidental complexity: An empirical look at teaching and using C++ – CppCon (2020)
• C.Carruth, T.Winters. What is C++ – CppCon (2019)

⚓

• Standard C++
• The C++ standards committee
• C++ standards committee papers
• C++ standard core language closed issues
• C++ standard draft sources
• C.Carruth et al. Goals and priorities for C++ – WG21/P2137

Abstract machine

❔

• Undefined, unspecified and implementation-defined behavior – Stack Overflow

🎥

• B.Steagall. Back to basics: The abstract machine – CppCon (2020)

---

ABI and implementation

🔗

• Binary compatibility issues with C++ – KDE wiki
• ABI stability – Android Open Source Project
• The ABI generic analysis and instrumentation library

🎥

• M.Clow. What is an ABI, and why is breaking it a problem? – C++Now (2021)
• M.Clow. What is an ABI, and why is breaking it bad? – CppCon (2020)
• L.Dionne. The C++ ABI from the ground up – CppCon (2019)

⚓

• T.Winters. What is ABI, and what should WG21 do about it? – WG21/P2028
• T.Winters. ABI – Now or never – WG21/P1863
• L.Dionne. Controlling the instantiation of vtables and RTTI – WG21/P1263

Itanium C++ ABI

The Itanium C++ ABI is an ABI for C++. As an ABI, it gives precise rules for implementing the language, ensuring that separately-compiled parts of a program can successfully interoperate. It is not platform-specific and can be layered portably on top of an arbitrary C ABI. It is used as the standard C++ ABI for many major operating systems on all major architectures, and is implemented in many major C++ compilers, including GCC and Clang.

🔗

• Itanium C++ ABI

Calling conventions

🔗

• R.Orr. Windows 64-bit calling conventions – Overload 120 (2014)

Implementation of inheritance

🔗

• D.Saks. Stepping up to C++: How virtual functions work – C/C++ Users Journal 12 (1994)

❔

• Virtual table layout of multiple inheritance – Stack Overflow

📖

• Ch. 1: Inheritance, Sec.: Inheritance implementation; Ch. 2: Multiple inheritance, Sec.: Multiple inheritance implementation – N.Llopis. C++ for game programmers – Charles River Media (2003)

Implementation of exceptions

See also Exceptions – Patterns, idioms, and design principles.

🔗

• V.Kochhar. How a C++ compiler implements exception handling (2002)

🎥

• A.Weis. Exceptions demystified – C++Now (2019)
• J.McNellis. Unwinding the stack: Exploring how C++ exceptions work on windows – CppCon (2018)
• D.Watson. C++ exceptions and stack unwinding – CppCon (2017)

⚓

• Exception handling – Itanium C++ ABI

---

Keywords

🔗

• H.Sutter. Keywords that aren’t (or, comments by another name) – Dr.Dobb’s Journal (2003)

---

Attributes

❔

• In a lambda, what does the second list of attributes do? – Stack Overflow

🎥

• B.Saks. Better code with C++ attributes – CppCon (2019)

[[maybe_unused]]

See also Unused variables and return values – Patterns, idioms, and design principles.

[[likely]] / [[unlikely]]

These attributes allow the compiler to optimize for the case where paths of execution are more or less likely than any alternative path of execution.

See [[likely]] / [[unlikely]] attributes – Hardware, optimization, and OS internals.

[[nodiscard]]

This attribute encourages the compiler to issue a warning if the return value is discarded. Conservative approach suggested by N.Josuttis:

• Should be added:
  • existing APIs: not using the return value always is a “huge mistake”; not using the return value is a source of trouble and easily can happen;
  • new APIs: not using the return value is usually an error.
• Should not be added:
  • existing APIs: not using the return value is a possible/common way of programming at least for some input; not using the return value makes no sense but doesn’t hurt.

🔗

• What’s the reason for not using C++17’s [[nodiscard]] almost everywhere in new code? – Software Engineering

⚓

• N.Josuttis. [[nodiscard]] in the library – WG21/P0600

[[noreturn]]

This attribute indicates that the function does not return.

🔗

• A.O’Dwyer. void versus [[noreturn]] (2022)

❔

• What is the point of [[noreturn]]? – Stack Overflow

⚓

• C++ attribute: noreturn – C++ reference

[[trivially_relocatable]]

This attribute specifies that the relocation operation for an object is trivial: moving the object and then immediately destroying the original is equivalent to memcpy. This attribute is not yet in the standard.

See Relocation – Memory – Optimization and hardware.

---

Declarations

🔗

• D.Saks. The column that needs a name: Understanding C++ declarations – C/C++ Users Journal 14 (1996)
• D.Anderson. The “clockwise/spiral rule”
• T.Parr. How to read C declarations
• C gibberish <-> English

🎥

• W.E.Brown. A medley of C++: The principle behind C++ declaration syntax – C++ on Sea (2022)
• H.Hinnant. How to initialize x from expression y – Meeting C++ (2019)
• D.Saks. East const but constexpr West – code::dive (2018)

alignas and alignment

See also Layout – Class types.

⚓

• alignas specifier – C++ reference

auto

For variables, specifies that the type of the variable will be automatically deduced from its initializer. For functions, specifies that the return type will be deduced from its return statements. For non-type template parameters, specifies that the type will be deduced from the argument.

🔗

• H.Sutter. GotW #92: auto variables, Part 1 (2013)
• H.Sutter. GotW #93: auto variables, Part 2 (2013)
• H.Sutter. GotW #94: AAA style (almost always auto) (2013)
• R.Orr. auto – A necessary evil? (Part II) – Overload 116 (2013)
• R.Orr. auto – A necessary evil? – Overload 115 (2013)

❔

• C++11 – declaring non-static data members as auto – Stack Overflow
• Does auto make C++ code harder to understand? – Software Engineering

const and mutable

In C++98: const means “logically const”, in C++11 const means “thread safe” (bitwise const or internally synchronized). In C++98: mutable means “not observably non-const”, in C++11 mutable means “thread safe” (bitwise const or internally synchronized).

🔗

• Const correctness – C++ FAQ
• H.Sutter. GotW #6: Const-correctness
• A.O’Dwyer. const is a contract (2019)
• S.Meyers. Appearing and disappearing consts in C++ (2011)
• D.Saks. Stepping up to C++: Mutable class members – C/C++ Users Journal 13 (1995)

❔

• Use of const for function parameters – Stack Overflow
• C++ const keyword – use liberally? – Stack Overflow

🎥

• H.Sutter. You don’t know const and mutable – C++ and Beyond (2012)

⚓

• ES.28: Use lambdas for complex initialization, especially of const variables – C++ core guidelines

constexpr

🔗

• J.Müller. constexpr is a platform (2020)
• B.Revzin. The constexpr array size problem (2020)
• A.Krzemieński. constexpr function is not const (2013)

❔

• Why is a constexpr function on a reference not constexpr? – Stack Overflow
• Why do we need to mark functions as constexpr? – Stack Overflow
• Detecting constexpr with SFINAE – Stack Overflow
• Should I mark a compiler-generated constructor as constexpr? – Stack Overflow
• Why disallow goto in constexpr functions? – Stack Overflow
• The value of a const variable is or is not usable in a constant expression, depending on the variable type – Stack Overflow
• Can you call a static constexpr member function at compile time? – Stack Overflow

🎥

• S.Schurr. constexpr: Introduction, Applications – CppCon (2015)

⚓

• B.Revzin. Using unknown pointers and references in constant expressions – WG21/P2280

constexpr and dynamic allocations

❔

• C++20 constexpr vector and string not working – Stack Overflow

consteval

❔

• Will consteval functions allow template parameters dependent on function arguments? – Stack Overflow

decltype and std::declval()

The decltype specifier inspects the declared type of an entity or the type and value category of an expression. std::declval converts any type T to a reference type, making it possible to use member functions in the operand of the decltype specifier without the need to go through constructors.

🔗

• A.O’Dwyer. decltype of a non-static member (2021)

❔

• Why does std::declval add a reference? – Stack Overflow

⚓

• decltype specifier – C++ reference

enum, enum class

🔗

• S.Dargo. Bitwise enumerations (2022)
• A.Williams. Using enum classes as bitfields (2015)

❔

• Is it safe to reinterpret_cast an enum class variable to a reference of the underlying type? – Stack Overflow
• Using reinterpret_cast on an enum class – valid or undefined behavior? – Stack Overflow
• Are C++ enums signed or unsigned? – Stack Overflow

⚓

• Enumeration declaration – C++ reference
• What is the type of an enumeration such as enum Color? Is it of type int? – C++ FAQ
• If an enumeration type is distinct from any other type, what good is it? What can you do with it? – C++ FAQ

friend

🎥

• D.Saks. Making new friends – CppCon (2018)

Friend function templates

See Friend function templates – Function templates – Templates.

Hidden friends

🔗

• A.Williams. The power of hidden friends in C++ (2019)

🎥

• P.Bindels. Crouching tiger, hidden friend – ACCU (2023)

⚓

• W.E.Brown, D.Sunderland. Recommendations for specifying “hidden friends” – WG21/P1601

inline

🔗

• P.Arias. Inline variables and functions (2019)

❔

• One Definition Rule – multiple definition of inline functions – Stack Overflow
• Does it make any sense to use inline keyword with templates? – Stack Overflow

⚓

• inline specifier – C++ reference

static

❔

• Static variables in an inlined function – Stack Overflow
• What is a static function in C? – Stack Overflow

static_assert

⚓

• static_assert declaration – C++ reference
• B.Revzin. Allowing static_assert(false) – WG21/P2593

using

🔗

• S.Dargo. The 4 use of using in C++ (2022)

❔

• A using statement compiles with g++, fails compilation with clang – Stack Overflow
• About the ambiguity of using a name vs using a namespace when doing unqualified calls – Stack Overflow

using enum

⚓

• Using-enum-declaration – C++ reference
• G.Ažman, J.Müller. Using enum – WG21/P1099

Elaborated type specifier

⚓

• Elaborated type specifier – C++ reference

Flexible array member

🔗

• Flexible array member – Wikipedia

❔

• Are flexible array members valid in C++? – Stack Overflow
• Is using flexible array members in C bad practice? – Stack Overflow

Most vexing parse

There is an ambiguity in the grammar involving expression-statements and declarations: An expression-statement with a function-style explicit type conversion as its leftmost subexpression can be indistinguishable from a declaration where the first declarator starts with a (. In those cases the statement is a declaration.

🔗

• H.Sutter. GotW #75: Istream initialization?
• D.Kalev. Overcoming the “most vexing parse” problem (2009)

📖

• Item 6: Be alert for C++’s most vexing parse – S.Meyers. Effective STL: 50 Specific ways to improve your use of the standard template library – Addison-Wesley (2001)

⚓

• [stmt.ambig] Statements: Ambiguity resolution – C++ standard draft

Namespaces

🔗

• A.Fertig. static, inline, or an unnamed namespace what’s the difference (2023)

❔

• Wherefore inline unnamed namespaces? – Stack Overflow

⚓

• Namespaces – C++ reference

Storage class specifiers

🔗

• A.Fertig. static, inline, or an unnamed namespace what’s the difference (2023)
• What is external linkage and internal linkage? – Stack Overflow
• P.Goldsborough. Internal and external linkage in C++ (2016)
• J.Schilling. Extern inlines by default (2001)

🎥

• D.Saks. Storage duration and linkage in C and C++ – NDC TechTown (2019)

⚓

• Storage class specifiers – C++ reference

Structured binding

🔗

• S.Brand. Adding C++17 structured bindings support to your classes (2016)

❔

• Understand structured binding in C++17 by analogy – Stack Overflow
• Why are structured bindings defined in terms of a uniquely named variable? – Stack Overflow
• Structured bindings and tuple of references – Stack Overflow

⚓

• Structured binding declaration – C++ reference
• B.Revzin, J.Wakely. Structured bindings can introduce a pack – WG21/P1061
• N.Lesser. Extending structured bindings to be more like variable declarations – WG21/P1091

---

Initialization

🔗

• A.O’Dwyer. PSA: Value-initialization is not merely default-construction (2023)
• P.Arias. Initialization of static variables (2020)
• C.McClure. C++ object initialization
• B.Filipek. What happens to your static variables at the start of the program? (2018)
• S.Brand. Initialization in C++ is bonkers – Overload 139, 9 (2017)
• E.Martin. Static initializers (2011)
• A.Demin. The difference between new T() and new T (in Russian, 2009)

❔

• Is C++11 uniform initialization a replacement for the old style syntax? – Software Engineering
• Can T t = {}; and T t{}; produce different results? – Stack Overflow

⚓

• Initialization – C++ reference

Aggregate initialization

🔗

• A.Fertig. Aggregates: C++17 vs. C++20 (2024)

❔

• What are aggregates and PODs and how/why are they special? – Stack Overflow

⚓

• Aggregate initialization – C++ reference

Uniform initialization

🔗

• A.Fertig. Evaluation order in C++ and uniform initialization (2023)

constinit

❔

• What is constinit in C++20? – Stack Overflow

---

Dynamic memory

🔗

• D.Saks. C++ theory and practice: new and delete – C/C++ Users Journal 15 (1997)

❔

• How do compilers use “over-allocation” to remember the number of elements in an allocated array? – C++ FAQ
• How do compilers use an “associative array” to remember the number of elements in an allocated array? – C++ FAQ
• Treating memory returned by operator new(sizeof(T) * N) as an array – Stack Overflow
• Why should C++ programmers minimize use of new? – Stack Overflow
• Difference between new and operator new? – Stack Overflow

📖

• Sec. 19.2.5: Allocation and deallocation – B.Stroustrup. The C++ programming language – Addison-Wesley (2013)
• Item 8: Understand the different meanings of new and delete – S.Meyers. More effective C++: 35 new ways to improve your programs and designs – Addison-Wesley (1996)
• Ch. 10: Memory management – B.Stroustrup. The design and evolution of C++ – Addison-Wesley (1994)

⚓

• Low level memory management – C++ reference
• R.10: Avoid malloc() and free() – C++ core guidelines
• R.11: Avoid calling new and delete explicitly – C++ core guidelines

Alignment

🔗

• B.Filipek. New new(): The C++17’s alignment parameter for operator new() (2019)

⚓

• C.Nelson. Dynamic memory allocation for over-aligned data – WG21/P0035

Object creation and placement new

See also Uninitialized storage – The standard library and proposals.

❔

• Array placement-new requires unspecified overhead in the buffer? – Stack Overflow
• Is using malloc for int undefined behavior until C++20 – Stack Overflow

🎥

• C.J.Johnson. How to hold a T – CppCon (2019)

⚓

• R.Smith. Implicit creation of objects for low-level object manipulation – WG21/P0593
• B.Hutchings. Determining the buffer size for placement new – WG21/CWG issue 476 (2004)
• T.Koeppe. C++ DR about global placement array new – WG21/EWG issue 68 (2013)

Global replacement of operator new and operator delete

❔

• How to properly replace global new and delete operators – Stack Overflow
• Is it possible to replace the global operator new everywhere? – Stack Overflow

⚓

• operator new, operator new[]: Global_replacements – C++ reference

---

Exceptions

See also Exceptions – Patterns, idioms, and design principles and Exceptions – The standard library and proposals.

🔗

• R.McArdell. C++11 (and beyond) exception support – Overload 141 (2017)

❔

• B.Stroustrup. Why doesn’t C++ provide a finally construct? – C++ style and technique FAQ
• Is there any difference between noexcept and empty throw specification for an lambda expression? – Stack Overflow
• Losing exception type when rethrowing an exception from a catch block – Stack Overflow

noexcept specifier

Specifies whether a function could throw exceptions.

⚓

• noexcept specifier – C++ reference

---

Expressions

nullptr

The keyword nullptr denotes the pointer literal. It is a prvalue of type std::nullptr_t.

See std::nullptr_t – The standard library and proposals.

Compound literals

A compound literal constructs an unnamed object of specified type in-place: ( type ) { initializer-list }.

🔗

• R.Meyers. The new C: Compound literals – Dr.Dobb’s Journal (2001)

❔

• Are compound literals standard C++? – Stack Overflow

⚓

• Compound literals – C++ reference

User-defined literals

A user-defined literal (UDL) allows integer, floating-point, character, and string literals to produce objects of user-defined type by defining a user-defined suffix.

🔗

• A.O’Dwyer. Namespaces for UDLs (2018)

⚓

• User-defined literals – C++ reference

Operator precedence and associativity

❔

• Who defines C operator precedence and associativity, and how does it relate to order of evaluation? – Stack Overflow
• What is the relation between operator precedence and order of evaluation? – Stack Overflow

⚓

• C++ operator precedence – C++ reference

Order of evaluation

🔗

• E.Lippert. Precedence vs associativity vs order (2008)
• P.Becker. Questions & Answers – C/C++ Users Journal 16 (1998)

❔

• What is the relation between operator precedence and order of evaluation? – Stack Overflow
• Who defines C operator precedence and associativity, and how does it relate to order of evaluation? – Stack Overflow
• Undefined behavior and sequence points – Stack Overflow

📖

• T.Cargill. A dynamic vector is harder than it looks – S.B.Lippman. C++ gems: Programming pearls from The C++ report (1997)

⚓

• Order of evaluation – C++ reference

Type conversions

❔

• When should static_cast, dynamic_cast, const_cast, and reinterpret_cast be used? – Stack Overflow

📖

• Item 2: Prefer C++-style casts – S.Meyers. More effective C++: 35 new ways to improve your programs and designs – Addison-Wesley (1996)

dynamic_cast

🔗

• A.O’Dwyer. Classically polymorphic visit replaces some uses of dynamic_cast (2020)

❔

• C++ equivalent of Java’s instanceof – Stack Overflow
• dynamic_cast with RTTI disabled – Stack Overflow

🎥

• A.O’Dwyer. dynamic_cast from scratch – CppCon (2017)

⚓

• dynamic_cast conversion – C++ reference

Type punning

📝

• Since C++20, some of type punning can be done using std::bit_cast, see std::bit_cast – The standard library and Boost.

🔗

• M.Sebor. The joys and perils of C and C++ aliasing. Part 1, Part II (2020)
• L.Torvalds. ... What’s the real reason for avoiding union aliasing? – Linux kernel mailing list (2018)
• S.Yaghmour. What is the strict aliasing rule and why do we care? (2018)
• M.Acton. Understanding strict aliasing (2006)

❔

• gcc, strict-aliasing, and horror stories – Stack Overflow
• What is the strict aliasing rule? – Stack Overflow
• Performance benefits of strict aliasing – Stack Overflow
• Gcc, strict-aliasing, and casting through a union – Stack Overflow
• Can I safely convert struct of floats into float array in C++? – Stack Overflow
• Reinterpret struct with members of the same type as an array in a standard compliant way – Stack Overflow

🎥

• T.Doumler. (How not to do) Type punning in modern C++ – CppCon (2019)

⚓

• Type punning – Wikipedia
• Options that control optimization: Type punning – GCC documentation

Value categories

🔗

• A.S.Knatten. lvalues, rvalues, glvalues, prvalues, xvalues, help! – Overload 150 (2019)
• B.Revzin. Value categories in C++17 (2017)

❔

• What categories (lvalue, rvalue, xvalue, etc.) can expressions that produce temporaries of class type fall into? – Stack Overflow
• Rvalues, lvalues and formal definitions – Stack Overflow

🎥

• W.E.Brown. A medley of C++: Exploring C++ value categories and the expression category taxonomy – C++ on Sea (2022)

⚓

• Value categories – C++ reference
• B.Stroustrup. “New” value terminology

---

Flow control

Range-based for loop

🔗

• S.Dargo. The infamous bug of range-based for loops (2022)
• M.Clow. Range based for loops and pairs of iterators (2013)

🎥

• D.Kühl. Range for – CppCon (2016)

if

⚓

• if statement – C++ reference

if constexpr

❔

• Difference between if constexpr() vs if() – Stack Overflow

switch

Transfers control to one of several statements, depending on the value of a condition.

🎥

• H.Wennborg. C++ switch statements under the hood in LLVM – StockholmCpp (2024)

⚓

• switch statement - C++ reference

---

Functions and function objects

❔

• Simplest way to determine return type of function – Stack Overflow
• C++ decltype deducing current function returned type – Stack Overflow

🎥

• B.Saks. Back to basics: Function call resolution in C++ – CppCon (2024)
• M.Shah. Back to basics: Functions in C++ – CppCon (2023)

Overload resolution

🔗

• Overload resolution between object, rvalue reference, const reference – Stack Overflow

Argument-dependent lookup

🔗

• What is “argument-dependent lookup” (aka ADL, or “Koenig lookup”)? – Stack Overflow
• A.O’Dwyer. What is ADL? (2019)
• A.O’Dwyer. ADL insanity (2019)
• A.O’Dwyer. How hana::type<T> “disables ADL” (2019)
• A.O’Dwyer. Avoid ADL calls to functions with common names (2018)
• A.O’Dwyer. WG21: Avoid creating ADL situations on functions with semi-common names (2018)

❔

• Why doesn’t ADL find function templates? – Stack Overflow

🎥

• J.Turner. Episode 160: Argument dependent lookup – C++ Weekly

⚓

• Argument-dependent lookup – C++ reference
• J.Spicer. ADL and function templates that are not visible – WG21/P0846

Function wrappers

std::function

❔

• Move-only version of std::function – Stack Overflow
• How to create an std::function from a move-capturing lambda expression? – Stack Overflow

⚓

• std::function – C++ reference

Lambda expressions

See also Lambda expression idioms – Patterns, idioms, and design principles.

🔗

• R.Chen. Non-capturing C++ lambdas can be converted to a pointer to function, but what about the calling convention? (2015)
• S.Meyers. C++14 lambdas and perfect forwarding (2013)
• S.Meyers. Lambdas vs. closures (2013)
• A.Allain. Lambda functions in C++11 – the definitive guide (2011)

❔

• What is the need of template lambda introduced in C++20 when C++14 already has generic lambda? – Stack Overflow
• What is a lambda expression in C++11? – Stack Overflow
• Why are lambda expressions not allowed in an unevaluated operands but allowed in the unevaluated portions of constant expressions? – Stack Overflow
• Can we get the type of a lambda argument? – Stack Overflow
• Why is a const variable sometimes not required to be captured in a lambda? – Stack Overflow
• In a lambda, what does the second list of attributes do? – Stack Overflow

🎥

• W.E.Brown. A medley of C++: Why are they named lambdas? – C++ on Sea (2022)
• R.Orr. Let’s look at lambdas – ACCU (2021)
• B.Geller, A.Sermersheim. Back to basics: Lambda expressions – CppCon (2020)
• B.Deane. C++20 lambdas: Familiar template syntax – CppCon (2020)
• A.O’Dwyer. Back to basics: Lambdas from scratch – CppCon (2019)

⚓

• L.Dionne, H.Tong. Wording for lambdas in unevaluated contexts – WG21/P0315
• L.Dionne. Familiar template syntax for generic lambdas – WG21/P0428

Member functions

Member function poiners

🔗

• A.Fertig. Calling a C++ member function with a null object (2024)
• A.Fertig. The power of ref-qualifiers (2022)
• V.Lazarenko. Why C++ member function pointers are 16 bytes wide (2013)
• R.Chen. Pointers to member functions are very strange animals (2004)
• C.Skelly. Powerful pointers to member functions – C/C++ Users Journal 12 (1994)

⚓

• Pointers to member functions – C++ FAQ

Special member functions

🎥

• K.van Rens. Special member functions in C++ – C++ on Sea (2023)

Explicit object parameter / deducing this

🔗

• S.Brand. C++23’s deducing this: what it is, why it is, how to use it

Deleted functions (= delete;)

If, instead of a function body, the special syntax = delete; is used, the function is defined as deleted. Any use of a deleted function is ill-formed (the program will not compile).

🔗

• A.O’Dwyer. Refactoring with =delete (2022)
• A.O’Dwyer. What =delete means (2021)
• A.Knatten. No move vs deleted move constructors – Overload 166 (2021)
• A.Knatten. The difference between no move constructor and a deleted move constructor (2021)

⚓

• Deleted functions – C++ reference

main()

🔗

• E.Bendersky. How statically linked programs run on Linux (2012)

🎥

• M.Godbolt. The bits between the bits: How we get to main() – CppCon (2018)

⚓

• Main function – C++ reference

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Operators

❔

• What are the basic rules and idioms for operator overloading? – Stack Overflow

🎥

• B.Deane. Operator overloading: History, principles and practice – CppCon (2018)

⚓

• operator overloading – C++ reference
• Canonical implementations – C++ reference

Comparisons

🔗

• J.Müller. Mathematics behind comparison (2018)

⚓

• Comparison operators – C++ reference

Three-ways comparisons

🔗

• B.Revzin. Implementing the spaceship operator for optional – Overload 147 (2018)

🎥

• L.de Cock. Space invaders: The C++20 spaceship operator is upon us – ACCU (2023)
• W.E.Brown. A C++20 preview: operator<=> – CppCon (2017)

⚓

• Default comparisons – C++ reference
• D.Stone. I did not order this! Why is it on my bill? – WG21/P1190

Pointer comparisons

🔗

• A.O’Dwyer. Pointer comparisons with std::less<void>: a horror story (2019)
• K.Walfridsson. C pointers are not hardware pointers (2016)

⚓

• Pointer comparison operators – C++ reference

Conditional operator ?:

🔗

• K.Pugh. Using the conditional operator ?: – C/C++ Users Journal 10 (1992)

Logical operators

Implication

🔗

• In support of implication for C++ (2023)

⚓

• W.E.Brown. Implication for C++ – WG21/P2971

sizeof / alignof

The sizeof operator yields the size in bytes of the object or type. When applied to a class type, the result is the size of an object of that class plus any additional padding required to place such object in an array. The alignof operator returns the alignment required for any instance of a type.

❔

• Is it always the case that sizeof(T) >= alignof(T) for all object types T? – Stack Overflow

⚓

• sizeof operator – C++ reference
• alignof operator – C++ reference

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Types

❔

• What are the 15 classifications of types in C++? – Stack Overflow

🎥

• W.E.Brown. A medley of C++: The universe of C++ types – C++ on Sea (2022)
• B.Milewski. Why algebraic data types are important – code::dive (2018)

void

❔

• How much existing C++ code would break if void was actually defined as struct void {}; – Stack Overflow

⚓

• Void type – C++ reference

Integral types

🔗

• J.Müller. New integer types I’d like to see (2022)
• W.Dietz et al. Understanding integer overflow in C/C++ – Proc. ICSE (2012)
• Rule 04. Integers – SEI CERT C coding standard

❔

• Compiler optimizations may cause integer overflow. Is that okay? – Stack Overflow
• Why does integer overflow on x86 with GCC cause an infinite loop? – Stack Overflow
• Why does this loop produce “warning: iteration 3u invokes undefined behavior” and output more than 4 lines? – Stack Overflow
• Does a long ban make sense? – Software Engineering

🎥

• R.Seacord. Integer type selection in C++ in safe, secure and correct code – C++ Now (2023)
• J.Bastien. Signed integers are two’s complement – CppCon (2018)
• D.Saks. Choosing the right integer types in C and C++ – code::dive (2018)

⚓

• J.Bastien. Signed integers are two’s complement – WG21/P0907

Integral promotion

❔

• Implicit type conversion rules in C++ operators – Stack Overflow
• Why do unsigned “small” integers promote to signed int? – Stack Overflow

⚓

• Integral promotion – C++ reference

wchar_t

🔗

• wchar_t is a historical accident (2017)

Floating-point types

There are three floating point types: float, double, and long double. The type double provides at least as much precision as float, and the type long double provides at least as much precision as double. The set of values of the type float is a subset of the set of values of the type double; the set of values of the type double is a subset of the set of values of the type long double. The value representation of floating-point types is implementation-defined.

See also Floating-point arithmetic – Numeric data structures and algorithms.

🔗

• D.Howard. Byte swapping floating point types (2007)
• Semantics of floating point math in GCC – GCC Wiki
• *Compiler options: /fp (specify floating-point behavior) – Visual C++ documentation
• Handling overflow when casting doubles to integers in C – Stack Overflow

❔

• When do you use float and when do you use double – Software Engineering

⚓

• P.A.Bristow, C.Kormanyos, J.Maddock. Floating-point typedefs having specified widths – WG14/N1703
• P.A.Bristow, C.Kormanyos, J.Maddock. Floating-point typedefs having specified widths – WG21/N3626

__float128

🔗

• long double (GCC specific) and __float128 – Stack Overflow
• How to use GCC 4.6.0 libquadmath and __float128 on x86 and x86_64 – Stack Overflow

⚓

• Additional floating types – GCC documentation

Trivial and POD types

🔗

• Trivial, standard-layout, POD, and literal types – Visual C++ language reference (2018)
• Trivial vs. standard layout vs. POD – Stack Overflow

Pointer and array types

❔

• Can C arrays contain padding in between elements? – Stack Overflow
• One-dimensional access to a multidimensional array: is it well-defined behaviour? – Stack Overflow

🎥

• B.Saks. Back to basics: Pointers and memory – CppCon (2020)

Null pointers

⚓

• Null pointers – C programming FAQs

Class types

❔

• Is C++ allowed to increase the derived class size if there are no new member variables compared to the base class? – Stack Overflow

🎥

• R.Powell. Intro to the C++ object model – CppCon (2015)

⚓

• Class declaration – C++ reference

Destructors

🔗

• A.Fertig. When an empty destructor is required (2023)
• A.Fertig. Why you shouldn’t provide an empty destructor (2023)

⚓

• Destructors – C++ reference

Layout

🔗

• S.Dargo. Make declaration order layout mandated (2022)
• E.S.Raymond. The lost art of structure packing
• E.Bendersky. Dumping a C++ object’s memory layout with Clang (2012)

❔

• Structure padding and packing – Stack Overflow
• Passing reference of packed struct member to template – GCC bug? – Stack Overflow

🎥

• S.Dewhurst. Back to basics: Class layout – CppCon (2020)

⚓

• C++ named requirements: StandardLayoutType – C++ reference
• std::is_standard_layout – C++ reference
• std::has_unique_object_representations – C++ reference
• P.Balog. Make declaration order layout mandated – WG21/P1847

Member functions

See Functions and function objects – Member functions.

Polymorphism and inheritance

See also Implementation of inheritance – ABI and implementation.

🔗

• S.Pamudurthy. Polymorphism in C++ – A type compatibility view – Overload 141 (2017)
• E.de Vries. Memory layout for multiple and virtual inheritance (2006)

❔

• Inheritance — Multiple and virtual inheritance – C++ FAQ

:movie_camera

• I.Bogosavljevic. The hidden performance price of C++ virtual functions – CppCon (2022)

📖

• Ch. 1: Inheritance, Ch. 2: Multiple inheritance – N.Llopis. C++ for game programmers – Charles River Media (2003)

Union types

❔

• B.Stroustrup. unions (generalized) – C++11 - the new ISO C++ standard

⚓

• Union declaration – C++ reference

Function types

⚓

• A.Meredith. Abominable function types – WG21/P0172

References

❔

• Is null reference possible? – Stack Overflow

Lifetime of a temporary

🔗

• T.Winters. TotW #107: Reference lifetime extension` – Abseil C++ Tips (2015)

❔

• Does a const reference class member prolong the life of a temporary? – Stack Overflow

:movie_camera

• A.Schödl. The C++ rvalue lifetime disaster – CoreHard (2019)

⚓

• Lifetime of a temporary – C++ reference

Rvalue references, universal references, and move semantics

See also Move semantics – Patterns, idioms, and design principles.

🔗

• R.Chen. On harmful overuse of std::move (2023)
• A.O’Dwyer. Don’t forward things that aren’t forwarding references (2023)
• C.DaCamara. Improving the state of debug performance in C++ (2022)
• J.Müller. Implementation сhallenge: Replacing std::move and std::forward (2020)
• H.E.Hinnant et al. A brief introduction to rvalue references (2008)
• Rvalue reference declarator: && – Microsoft Visual C++ (2016)
• T.Becker. C++ rvalue references explained (2013)
• S.Meyers. C++14 lambdas and perfect forwarding (2013)
• S.Meyers. Universal references in C++11 (mirror) – Overload 111, 8 (2012)
• E.Bendersky. Understanding lvalues and rvalues in C and C++ (2011)

❔

• What is move semantics? – Stack Overflow
• Rvalues, lvalues and formal definitions – Stack Overflow
• Pass by value vs pass by rvalue reference – Stack Overflow
• Rvalues and move semantics with return statement – Stack Overflow
• The implementation of std::forward – Stack Overflow
• Advantages of using forward – Stack Overflow
• Do rvalue references to const have any use? – Stack Overflow
• What does auto&& tell us? – Stack Overflow

🎥

• A.Kirsh. To move or not to move: An interactive analysis – CppNorth (2023)
• N.Josuttis. The hidden secrets of move semantics – CppCon (2020)
• D.Olsen. Back to basics: Move semantics – CppCon (2020)
• K.Iglberger. Back to basics: Move semantics. Part I, Part II – CppCon (2019)
• A.Schödl. The C++ rvalue lifetime disaster – CoreHard (2019)
• N.Josuttis. The nightmare of move semantics for trivial classes – CppCon (2017)

⚓

• B.Stroustrup. “New” value terminology

Opaque typedefs

See Opaque typedef – Patterns, idioms, and design principles.

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Standards

C++11

❔

• B.Stroustrup. C++11 - the new ISO C++ standard

C++14

🔗

• M.Nelson. The C++14 standard: What you need to know – Dr.Dobb’s Journal (2014)
• A.Krzemieński. constexpr function is not const (2013)

C++17

🎥

• N.Josuttis. C++17 : The biggest traps – C++ on Sea (2019)
• N.Josuttis. C++17 – The best features - ACCU (2018)
• B.A.Lelbach. C++17 features. Part I, Part II – CppCon (2017)
• A.Meredith. C++17 in breadth (not depth). Part I, Part II – CppCon (2016)

⚓

• C++17 compiler support – C++ reference

C++20

🔗

• S.Dargo. My first work experience with C++20 (2022)

🎥

• A.Williams. An introduction to multithreading in C++20 – CppCon (2022)
• N.Josuttis. C++20: My favourite code examples – ACCU (2022)
• N.Josuttis. C++20: My favourite code examples – Meeting C++ (2021)
• B.Deane. C++20 lambdas: Familiar template syntax – CppCon (2020)
• F.Cooper. C++20: All the small things – C++ on Sea (2020)
• B.Stroustrup. C++20: C++ at 40 – CppCon (2019)
• A.Meredith. How C++20 can simplify std::tuple – ACCU (2019)

⚓

• Compiler support for C++20 – C++ reference

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Tricks and subtleties

🔗

• A.O’Dwyer. Hidden reinterpret_casts (2020)

❔

• Hidden features of C++ – Stack Overflow
• Why compilers test the least significant bit in an address? – Stack Overflow
• Why does the size of class in C++ depend on the public/private status of data members? – Stack Overflow
• Difference between struct and typedef struct in C++? – Stack Overflow
• What are “extern char condition tricks”? – Stack Overflow
• Why can I use scalar type as the return type of operator->? – Stack Overflow
• What is the worst real-world macros/pre-processor abuse you’ve ever come across? – Stack Overflow

🎥

• JF Bastien. *(char*)0 = 0; – C++ on Sea (2023)
• J.Müller . C++ features you might not know – C++ on Sea (2023)
• M.Kruse. v.~uint32_t(); – CppCon (2019)
• J.Wakely, M.Clow. These 10 tricks that only library implementors know! – ACCU (2018)

Accessing private and protected members

🔗

• J.Schaub. Access to private members. That’s easy! (2010))

❔

• Accessing private members – Stack Overflow

Embedding binary data

🔗

• D.Weiler. incbin – Include binary files in C/C++
• H.Landau. Embedding of binary data into programs

❔

• Embedding resources in executable using GCC – Stack Overflow

⚓

• J. Meneide. std::embed – WG21/P1040

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C, C vs C++

🔗

• A.Weissflog. Modern C for C++ peeps (2019)
• Linus Torvalds on C++ (2007)
• J.Nieminen. A response to Linus Torvalds on C++ (2007)
• D.R.Tribble. Incompatibilities between ISO C and ISO C++ (2001)

❔

• What are the fundamental differences between C and C++? – Software Engineering
• Why should we typedef a struct so often in C? – Stack Overflow
• Size of character ('a') in C/C++
• Is there any reason to use C++ instead of C, Perl, Python, etc.? – Software Engineering
• When to use C over C++, and C++ over C? – Software Engineering
• Is the C programming language still used? – Software Engineering

🎥

• D.Zalewski. C is great, long live C! Programming in modern C with a sneak peek into C23 – ACCU (2023)
• L.Sas. Modern C and what we can learn from it – ACCU (2021)

⚓

• C programming FAQs

Arrays

📖

• Essay 1: You must be joking – P.J.Plauger. Programming on purpose III: Essays on software technology (1994)

Functions

🔗

• A.Mertz. Calling C code from C++ with extern “C” (2018)

❔

• Call a C function from C++ code – Stack Overflow
• What kinds of C++ functions can be placed in a C function pointer? – Stack Overflow
• Passing lambdas as callbacks to C functions – Stack Overflow
• How to make a function with C-linkage from template? – Stack Overflow
• What is the difference between function() and function(void)? – Software Engineering

Static variables

❔

• Difference between initialization of static variables in C and C++ – Stack Overflow

Conditional operator

🔗

• P.Becker. Questions & Answers – C/C++ Users Journal 16 (1998)

❔

• Conditional operator differences between C and C++ – Stack Overflow