C++ identifier with special meaning:module(since C++20)

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

C++ language

General topics
Preprocessor Comments	Keywords Escape sequences
Flow control
Conditional execution statements
if	switch
Iteration statements (loops)
for range-for(C++11)	while do-while
Jump statements
continue - break	goto - return
Functions
Function declaration
Lambda function expression
inline specifier
Dynamic exception specifications(until C++17*)
noexcept specifier(C++11)
Exceptions
throw-expression try block	catch handler
Namespaces
Namespace declaration	Namespace aliases
Types
Fundamental types Enumeration types Function types	Class/struct types Union types
Specifiers
const/volatile decltype(C++11) auto(C++11)	constexpr(C++11) consteval(C++20) constinit(C++20)
Storage duration specifiers
Initialization
Default-initialization Value-initialization Zero-initialization Copy-initialization Direct-initialization	Aggregate initialization List-initialization(C++11)   Constant initialization Reference initialization

Expressions
Value categories Order of evaluation	Operators Operator precedence
Alternative representations
Literals
Boolean - Integer - Floating-point
Character - String - nullptr(C++11)
User-defined(C++11)
Utilities
Attributes(C++11)
Types
typedef declaration
Type alias declaration(C++11)
Casts
Implicit conversions static_cast const_cast	Explicit conversions dynamic_cast reinterpret_cast
Memory allocation
new expression	delete expression
Classes
Class declaration Constructors this pointer	Access specifiers friend specifier
Class-specific function properties
Virtual function override specifier(C++11)   final specifier(C++11)	explicit(C++11) static
Special member functions
Default constructor Copy constructor Move constructor(C++11)	Copy assignment Move assignment(C++11) Destructor
Templates
Class template Function template	Template specialization Parameter packs(C++11)
Miscellaneous
Inline assembly	History of C++

 

Keywords

alignas (C++11) alignof (C++11) and and_eq asm auto (*) bitand bitor bool break case catch char char8_t (C++20) char16_t (C++11) char32_t (C++11) class compl concept (C++20) const consteval (C++20) constexpr (C++11) constinit (C++20) const_cast continue contract_assert (C++26)   co_await (C++20) co_return (C++20) co_yield (C++20) decltype (C++11) default	delete do double dynamic_cast else enum explicit export extern false float for friend goto if inline int long mutable namespace new noexcept (C++11)   not not_eq nullptr (C++11) operator or or_eq private protected public	register reinterpret_cast requires (C++20) return short signed sizeof (*) static static_assert (C++11) static_cast struct switch template this thread_local (C++11) throw true try typedef typeid typename union unsigned using virtual void volatile wchar_t while xor xor_eq
Identifiers with special meaning
final (C++11) import (C++20) module (C++20)	override (C++11) post (C++26) pre (C++26)	replaceable_if_eligible (C++26) trivially_relocatable_if_eligible (C++26)

 

Usage

• module declaration: declares that the current translation unit is a module unit
• Starts a global module fragment of a module unit
• Starts a private module fragment of a module unit

Notes

Feature-test macro	Value	Std	Feature
__cpp_modules	201907L	(C++20)	Modules — core language support

Example

module;// starts a global module fragment   #include <string>   export module foo;// ends a global module fragment// declares the primary module interface unit for named module 'foo'// starts a module unit purview   export std::string f();   module :private;// ends the portion of the module interface unit that// can affect the behavior of other translation units// starts a private module fragment   std::string f(){return"foo";}

See also

• import, export
• private