std::real(std::complex)

 

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

 

Numerics library

Common mathematical functions
Mathematical special functions(C++17)
Mathematical constants(C++20)
Basic linear algebra algorithms(C++26)
Data-parallel types (SIMD)(C++26)
Floating-point environment(C++11)
Complex numbers
Numeric array (valarray)
Pseudo-random number generation
Bit manipulation(C++20)
Saturation arithmetic(C++26)
Factor operations
gcd (C++17)	lcm (C++17)
Interpolations
midpoint (C++20)	lerp (C++20)
Generic numeric operations
iota (C++11) ranges::iota (C++23) accumulate inner_product adjacent_difference    partial_sum	reduce (C++17) transform_reduce (C++17) inclusive_scan (C++17) exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
C-style checked integer arithmetic
ckd_add (C++26) ckd_sub (C++26)	ckd_mul (C++26)

 

std::complex

Member functions
complex::complex complex::operator= complex::real complex::imag	complex::operator+=complex::operator-=complex::operator*=complex::operator/=
Non-member functions
operator+operator- operator+operator-operator*operator/ operator==operator!= (until C++20)   operator<<operator>> get(std::complex) (C++26)	real imag abs arg norm conj proj (C++11) polar operator""ioperator""ifoperator""il (C++14)(C++14)(C++14)
Exponential functions
log   log10   exp
Power functions
pow   sqrt
Trigonometric functions
sin   cos tan asin (C++11) acos (C++11) atan (C++11)
Hyperbolic functions
sinh   cosh tanh asinh (C++11) acosh (C++11) atanh (C++11)
Helper types
tuple_size<std::complex> (C++26)
tuple_element<std::complex> (C++26)

 

Defined in header <complex>
	(1)
template<class T > T real(conststd::complex<T>& z );			(until C++14)
template<class T > constexpr T real(conststd::complex<T>& z );			(since C++14)
Additional overloads(since C++11)
Defined in header <complex>
		(A)
float       real(float f ); double      real(double f ); longdouble real(longdouble f );				(until C++14)
constexprfloat       real(float f ); constexprdouble      real(double f ); constexprlongdouble real(longdouble f );				(since C++14) (until C++23)
template<class FloatingPoint > constexpr FloatingPoint real( FloatingPoint f );				(since C++23)
			(B)
template<class Integer > double real( Integer i );					(until C++14)
template<class Integer > constexprdouble real( Integer i );					(since C++14)

1) Returns the real part of the complex number z, i.e. z.real().

A,B) Additional overloads are provided for all integer and floating-point types, which are treated as complex numbers with zero imaginary part.

(since C++11)

Parameters

z	-	complex value
f	-	floating-point value
i	-	integer value

Return value

1) The real part of z.

A)f.

B)static_cast<double>(i).

Notes

The additional overloads are not required to be provided exactly as (A,B). They only need to be sufficient to ensure that for their argument num:

• If num has a standard(until C++23) floating-point type T, then std::real(num) has the same effect as std::real(std::complex<T>(num)).
• Otherwise, if num has an integer type, then std::real(num) has the same effect as std::real(std::complex<double>(num)).

See also

real	accesses the real part of the complex number (public member function)
imag	returns the imaginary part (function template)
C documentation for creal