错误C2146:语法错误:缺少';'

Question

我讨厌在这样一个常见错误上寻求帮助,但我一直在盯着我的代码两个小时,试图找到编译器所说的缺少的分号和未指定的类型:

错误C2146:语法错误:缺少';' 在标识符'历史'之前.....:
错误C4430:缺少类型说明符 - 假设为int.注意:C++不支持default-int 1> c:\ users\alex\dropbox\lab4\lab4\lab4\customer.h(49):错误C4430:缺少类型说明符 - 假定为int.注意:C++不支持default-int

#pragma once

#include <string>
using std::string;
#include "customerdata.h"
#include "rentalhistory.h"
#include "item.h"
#include "customer.h"
/*---------------------------------------------------------------------------
Purpose: class Customer contains methods to grab information about a customer, 
such as their id number, address, phone number (stored in class CustomerData). 
It also contains methods that will allow access to information about a 
customer’s rental history (stored in class RentalHistory).

CONSTRUCTION:
(1) empty construction. (2) name and id (3) with information provided by
CustomerData object.
--------------------------------------------------------------------------- */
class Customer
{
public:
    Customer();
    Customer( const Customer & );
    Customer( string, string, int );
    Customer( const CustomerData & );
    ~Customer();

    // get customer's first name.
    string getFirstName() const;

    // get customer's last name.
    string getLastName() const;

    // get customer's id number
    int getIdNum() const;

    // add a movie to customer's rental history
    void addMovie( Item *&, string code );

    // checks to see if it is a valid customer
    bool isValidCustomer();

    // prints the customer's rental history
    void printHistory() const;

    Customer & operator=( Customer &rhs );


private:
    CustomerData data;  // object that contains customer's information
    RentalHistory history; // object that contains customer's rental history
};

Answer 1

该错误消息表明编译器无法识别RentalHistory为类型.如果在包含的内容中正确定义了类型rentalhistory.h,则此类问题的最常见原因将是循环依赖性.

是否rentalhistory.h尝试加入customer.h？在这种情况下,您需要解决循环包含问题.在rentalhistory.h你最有可能添加一个正向的声明一样class Customer;,而不是包括的customer.h.

另外:为什么要customer.h尝试包括自己？