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std::real(std::complex) - cppreference.com

From cppreference.com

Defined in header <complex> 

template< class T > 
T real( const std::complex<T>& z );
(1) (until C++14) 
template< class T > 
constexpr T real( const std::complex<T>& z );
(since C++14)

Additional overloads (since C++11)

Defined in header <complex> 

float       real( float f );
double      real( double f );
long double real( long double f );
(A) (until C++14) 
constexpr float       real( float f );
constexpr double      real( double f );
constexpr long double real( long double f );
(since C++14)
(until C++23)		 
template< class FloatingPoint >
constexpr FloatingPoint real( FloatingPoint f );
(since C++23) 
template< class Integer >
double real( Integer i );
(B) (until C++14) 
template< class Integer >
constexpr double 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