头文件无法识别包含的类

Question

我有两个.h文件和一个.cpp文件。当我编译.cpp文件时，它会导致错误：

错误：“雇员”尚未声明

虚拟无效提示（Employee＆a）= 0;

这使我感到困惑，因为我在文件中包含#include“ employee.h”。

我已经尝试过更改#include语句的顺序，但这并没有改变。

employee.h：

#ifndef EMPLOYEE
#define EMPLOYEE
#include "insurance.h"
#include <string>
#include <vector>

class Employee
{
public:
  bool quit;
  std::string name;
  float basesalary, commission, totalsalary;
  std::vector<Insurance*> sales;
  float ComputeSalary();
  virtual float ComputeCommission() = 0;
  virtual void Prompt() = 0;
};

#endif

employee.cpp：

#include "employee.h"

  float Employee::ComputeSalary()
  {
    totalsalary = basesalary + commission;
    return totalsalary;
  }

insurance.h：

#ifndef INSURANCE
#define INSURANCE
#include <string>
#include "employee.h"

class Insurance
{
public:
  std::string name, type;
  float commission;
  virtual float ComputeCommission() = 0;
  virtual void Prompt(Employee &a) = 0; // source of error!
};

#endif