complex<double>
描述可儲存皆為 double
類型之物件的有序對,第一個代表複數的實部,而第二個代表虛部。
語法
template <>
class complex<double> {
public:
constexpr complex(
double RealVal = 0,
double ImagVal = 0);
constexpr complex(const complex<double>& complexNum);
constexpr explicit complex(const complex<long double>& complexNum);
// rest same as class template complex
};
參數
RealVal
要建構之複數實際部分的 型 double
別值。
ImagVal
用於建構中複數虛部的 double
類型值。
complexNum
型別或 long double
型 float
別的複數,其實數和虛數部分用來初始化所建構之型 double
別的複數。
傳回值
double
類型的複數。
備註
類別樣板複雜至類型複雜類別的 double
明確特製化,只與類別範本在所定義的建構函式中不同。 從 轉換成 float
是隱含的,但從 long double
double
轉換成 必須是 explicit
。 double
使用 explicit
指派語法排除初始與型別轉換。
如需類別範本 complex
的詳細資訊,請參閱 複雜類別 。 如需類別範本 complex
的成員清單,請參閱 。
範例
// complex_comp_dbl.cpp
// compile with: /EHsc
#include <complex>
#include <iostream>
int main( )
{
using namespace std;
double pi = 3.14159265359;
// The first constructor specifies real & imaginary parts
complex <double> c1 ( 4.0 , 5.0 );
cout << "Specifying initial real & imaginary parts,\n"
<< "as type double gives c1 = " << c1 << endl;
// The second constructor initializes values of the real &
// imaginary parts using those of complex number of type float
complex <float> c2float ( 4.0 , 5.0 );
complex <double> c2double ( c2float );
cout << "Implicit conversion from type float to type double,"
<< endl << "gives c2double = " << c2double << endl;
// The third constructor initializes values of the real &
// imaginary parts using those of a complex number
// of type long double
complex <long double> c3longdouble ( 4.0 , 5.0 );
complex <double> c3double ( c3longdouble );
cout << "Explicit conversion from type float to type double,"
<< endl << "gives c3longdouble = " << c3longdouble << endl;
// The modulus and argument of a complex number can be recovered
double absc3 = abs ( c3longdouble );
double argc3 = arg ( c3longdouble );
cout << "The modulus of c3 is recovered from c3 using: abs ( c3 ) = "
<< absc3 << endl;
cout << "Argument of c3 is recovered from c3 using:" << endl
<< "arg ( c3 ) = " << argc3 << " radians, which is "
<< argc3 * 180 / pi << " degrees." << endl;
}
/* Output:
Specifying initial real & imaginary parts,
as type double gives c1 = (4,5)
Implicit conversion from type float to type double,
gives c2double = (4,5)
Explicit conversion from type float to type double,
gives c3longdouble = (4,5)
The modulus of c3 is recovered from c3 using: abs ( c3 ) = 6.40312
Argument of c3 is recovered from c3 using:
arg ( c3 ) = 0.896055 radians, which is 51.3402 degrees.
*/
需求
標頭 : < 複雜>
命名空間:std
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