C 11中的std :: complex的C 11复制赋值 – 与’operator’不匹配

下面的代码无法使用-std = c 0x开关使用g版本4.5.0进行编译.我收到以下错误消息：

error: no match for 'operator+' in 'std::pow [with _Tp = float,_Up = int,typename __gnu_cxx::__promote_2<_Tp,_Up>::__type = double](((const std::complex<float>&)((const std::complex<float>*)(& x))),((const int&)((const int*)(&2)))) + y'

我认为这与here提到的可分配要求有关.我应该为复杂定义我自己的复制赋值运算符吗？如果是这样,怎么样？

#include <complex>
using namespace std;

int main(int argc,char *argv[]) {
  complex<float> x,y;
  x = pow(x,2);      // ok
  x = x        + y;  // ok
  x = pow(x,2) + y;  // error
  return 0;
}

解决方法

[cmplx.over] / p3指定涉及复杂时的pow的额外重载：

Function template pow shall have additional overloads sufficient to
ensure,for a call with at least one argument of type complex<T>:

1. If either argument has type complex<long double> or type long double,then both arguments are effectively cast to complex<long
double>.

2. Otherwise,if either argument has type complex<double>,double,or an integer type,then both arguments are effectively cast to
   complex<double>.

3. Otherwise,if either argument has type complex<float> or float,then both arguments are effectively cast to complex<float>.

2被提升为double,而pow(complex< float>,double)返回复数< double>.