complex<double>

發行項
03/28/2013

將告訴您儲存已排序的成對的物件這兩種類型的物件雙*，* 第一次表示複合的數字和第二個真實的部分表示假想的部分。

template<>
   class complex<double> {
public:
   complex(
      double _RealVal = 0, 
      double _ImagVal = 0
   );

   complex(
      const complex<double>& _ComplexNum
   );
   explicit complex(
      const complex<long double>& _ComplexNum
   );
   // rest same as template class complex
};

參數

_RealVal
型別的值雙的複合的數字所建構的真實的部分。
_ImagVal
型別的值雙所建構的複數假想的一部份。
_ComplexNum
型別的複數浮點數或型別的long double的實際和虛構的部分用來初始化型別的複數雙精度浮點所建構。

傳回值

型別的複數雙。

備註

明確特製化樣板類別至複雜型別的類別複雜的雙差別只在其所定義的建構函式樣板類別。從轉換浮點數到雙不可為隱含的但從轉換long double到雙精度浮點都必須是明確。使用明確規則出初始化時使用指派語法的型別轉換。

如需有關該樣板類別complex，請參閱complex Class。為一系列的樣板類別成員complex，請參閱複雜的成員。

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,"
        << "\n 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,"
        << "\n 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:\n arg ( c3 ) = "
        << argc3 << " radians, which is " << argc3 * 180 / pi
        << " degrees." << endl;
}