NAME¶

std::complex::complex - std::complex::complex

Synopsis¶

Primary template (std::complex<T>) complex( const T& re (until = T(), const T& im = C++14) T() ); constexpr complex( (since const T& re = T(), C++14) const T& im = T() ); complex( const (until complex& other ); C++14) constexpr complex( (since const complex& other C++14) ); (until
C++23) constexpr complex( (since const complex& other C++23) ) = default; template< class X > (until complex( const C++14) complex<X>& other ); template< class X > (since constexpr complex( C++14) const complex<X>& (until other ); C++23) template< class X > constexpr explicit(/* see (since below */) complex( C++23) const complex<X>& other ); Standard explicit specialization std::complex<float> (until C++23) complex( float re = (until 0.0f, float im = C++11) 0.0f ); constexpr complex( (since float re = 0.0f, C++11) float im = 0.0f ); constexpr complex( const (2) (since complex<float>& C++20) other ) = default; explicit complex( const complex<double>& (until other ); C++11) explicit complex( const complex<long double>& other ); constexpr explicit complex( const complex<double>& other ); (since constexpr explicit C++11) complex( const complex<long double>& other ); Standard explicit (1) specialization std::complex<double> (until C++23) (2) complex( double re = (until 0.0, double im = 0.0 C++11) ); constexpr complex( (3) (since double re = 0.0, C++11) double im = 0.0 ); constexpr complex( const (2) (since complex<double>& C++20) other ) = default; complex( const complex<float>& other ); (1) (until explicit complex( C++11) const complex<long double>& other ); constexpr complex( const (3) complex<float>& other ); (since constexpr explicit C++11) complex( const complex<long double>& other ); Standard explicit specialization std::complex<long (1) double> (until C++23) complex( long double (until re = 0.0L, long C++11) double im = 0.0L ); (3) constexpr complex( long double re = (since 0.0L, long double im C++11) = 0.0L ); constexpr complex( const complex<long (2) (since double>& other ) = C++20) default; complex( const complex<float>& (1) other ); (until complex( const C++11) complex<double>& other ); constexpr complex( (3) const complex<float>& other ); (since constexpr complex( C++11) const complex<double>& other );

Constructs the std::complex object.
The standard explicit specializations (std::complex<float>, std::complex<double> and
std::complex<long double>) have different constructor declarations from the main
template.
(until C++23)

1) Constructs the complex number from real part re and imaginary part im.
2) Copy constructor. Constructs the object with the copy of the contents of other.
The copy constructors are implicitly declared in the standard explicit
specializations.
(until C++20)
3) Converting constructor. Constructs the object from a complex number of a
different type.

The main template provides a converting constructor template, while
each standard explicit specialization provides two non-template
constructors for the two other standard explicit specializations.
(until C++23)
The non-template constructors are converting constructors (i.e.
non-explicit) if and only if the conversions of the real and imaginary
parts are not narrowing.
For the main template, the expression inside explicit evaluates to
false if and only if the floating-point conversion rank of T is (since C++23)
greater than or equal to the floating-point conversion rank of X.

Parameters¶

re - the real part
im - the imaginary part
other - another complex number to use as source

Notes¶

Since C++23, the copy constructor is required to be trivial in order to satisfy the
TriviallyCopyable requirement, but implementations generally make it trivial in all
modes.

See also¶

operator= assigns the contents
(public member function)
operator""if
operator""i a std::complex literal representing purely imaginary number
operator""il (function)
(C++14)
C documentation for
CMPLX