在C ++中平均一组复数的正确方法是什么？

debugcn 发表于 Dev

我继承了一些C ++代码，需要平均一些复数。给定一个集合，它将添加那些将条件传递给累加器的值，然后除以所添加值的数量。

使用gcc（当前为gcc 8），template argument deduction/substitution failed如果我使用独立版本，我会得到，operator/但是它可以正常使用std::complex::operator/=。对于后续维护者来说，这样的细微差别似乎很脆弱。

那么获得复数平均值的正确方法是什么？

语言仅部分支持复数按整数类型的划分是否合理？

std::complex<double> A[32] = { /* initialization left to the reader */ };
int count = 0;

std::complex<double> sum;
for (auto i = 0; i < 32; ++i) {
   if ( i % 2 ) { // arbitrary condition, not important
      sum += A[i];
      ++count;
   }
}

auto avg = sum / count; // this is ambiguous
sum /= count;           // this is not

（代表错误，出于好奇）

main.cpp: In function ‘int main()’:
main.cpp:16:16: error: no match for ‘operator/’ (operand types are ‘std::complex<double>’ and ‘int’)
 auto avg = sum / count; // this is ambiguous
            ~~~~^~~~~~~
In file included from main.cpp:2:0:
/usr/include/c++/7/complex:434:5: note: candidate: template<class _Tp> std::complex<_Tp> std::operator/(const _Tp&, const std::complex<_Tp>&)
     operator/(const _Tp& __x, const complex<_Tp>& __y)
     ^~~~~~~~
/usr/include/c++/7/complex:434:5: note:   template argument deduction/substitution failed:
main.cpp:16:18: note:   mismatched types ‘const std::complex<_Tp>’ and ‘int’
 auto avg = sum / count; // this is ambiguous
                  ^~~~~
In file included from main.cpp:2:0:
/usr/include/c++/7/complex:425:5: note: candidate: template<class _Tp> std::complex<_Tp> std::operator/(const std::complex<_Tp>&, const _Tp&)
     operator/(const complex<_Tp>& __x, const _Tp& __y)
     ^~~~~~~~
/usr/include/c++/7/complex:425:5: note:   template argument deduction/substitution failed:
main.cpp:16:18: note:   deduced conflicting types for parameter ‘const _Tp’ (‘double’ and ‘int’)
 auto avg = sum / count; // this is ambiguous
                  ^~~~~
In file included from main.cpp:2:0:
/usr/include/c++/7/complex:416:5: note: candidate: template<class _Tp> std::complex<_Tp> std::operator/(const std::complex<_Tp>&, const std::complex<_Tp>&)
     operator/(const complex<_Tp>& __x, const complex<_Tp>& __y)
     ^~~~~~~~
/usr/include/c++/7/complex:416:5: note:   template argument deduction/substitution failed:
main.cpp:16:18: note:   mismatched types ‘const std::complex<_Tp>’ and ‘int’
 auto avg = sum / count; // this is ambiguous
                  ^~~~~

拉诺埃耶特普

不知道最适合进行除法的方法是什么，但是如果仔细检查所有参数operator/并operator/=采用，则会注意到：

operator/接受std::complex<T>或T。
- 因此，如果您使用创建了原始复合体double，则该复合体只能采用double或的另一个值complex<double>。
- 实际上，取决于您使用的编译器，clang直接给出了invalid operands to binary expression ('std::complex<double>' and 'int')错误
operator/=发生在std::complex<T>或T，同时还具有专业化float，double和long double。
- ，无论传递到手段operator/=将有一个变化是隐式转换为float，double或者long double，它int可以做。