Functions

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

C++ language

General topics
Preprocessor Comments Keywords	ASCII chart Escape sequences History of C++
Flow control
Conditional execution statements
if statement	switch statement
Iteration statements
for loop range-for loop (C++11)	while loop do-while loop
Jump statements
continue statement break statement	goto statement return statement
Functions
function declaration
lambda function declaration
function template
inline specifier
exception specifications (deprecated)
noexcept specifier (C++11)
Exceptions
throw expression	try-catch block
Namespaces
namespace declaration	namespace aliases
Types
fundamental types compound types enumeration types	union types function types
decltype specifier (C++11)
Specifiers
cv specifiers
storage duration specifiers
constexpr specifier (C++11)
auto specifier (C++11)
alignas specifier (C++11)
Initialization
default initialization value initialization zero initialization copy initialization direct initialization	aggregate initialization list initialization (C++11) constant initialization reference initialization

Literals
integer literals character literals floating-point literals string literals	boolean literals nullptr (C++11) user-defined (C++11)
Expressions
value categories order of evaluation	operators operator precedence
alternative representations
Utilities
Types
typedef declaration
type alias declaration (C++11)
attributes (C++11)
Casts
implicit conversions
const_cast conversion
static_cast conversion
dynamic_cast conversion
reinterpret_cast conversion
C-style and functional cast
Memory allocation
new expression	delete expression
Classes
class declaration this pointer access specifiers	friend specifier initializer lists
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

 

Functions are C++ entities that associate a sequence of statements (a function body) with a name and a list of function parameters.

When a function is invoked, e.g. in a function-call expression, the parameters are initialized from the arguments (either provided at the place of call or defaulted) and the statements in the function body are executed.

A function can terminate by returning or by throwing an exception.

A function declaration may appear in any scope, but a function definition may only appear in namespace scope or, for member and friend functions, in class scope. A function that is declared in a class body without a friend specifier is a class member function. Such functions have many additional properties, see member functions for details.

Functions are not objects: there are no arrays of functions and functions cannot be passed by value or returned from other functions. Pointers and references to functions are allowed, and may be used where functions themselves cannot.

Each function has a type, which consists of the function's return type, the types of all parameters (after array-to-pointer and function-to-pointer transformations, see parameter list), and, for member functions, cv-qualification and ref-qualification. Function types also have language linkage. There are no cv-qualified function types (not to be confused with the types of cv-qualified functions such as int f() const; or functions returning cv-qualified types, such as std::string const f();)

Unnamed functions can be generated by lambda-expressions.

Multiple functions in the same scope may have the same name, as long as their parameter lists and, for member functions, cv/ref qualifications are different. This is known as function overloading.