为什么为什么不断收到编译器错误“错误：'{'标记之前的预期类名”？

Question

我只是想从ArrayBag类继承公共成员函数，但我一直收到此“预期的类名”错误。我已包含文件并检查了拼写，但是错误仍然存​​在。我还确保在使用它们的地方包含适当的头文件。

$ra

#ifndef _ZOORECORD_HPP_
#define _ZOORECORD_HPP_

#include "ArrayBag.hpp"
#include "Animal.hpp"
#include <fstream>
#include <string>

class ZooRecord : public ArrayBag 
{
    public: 
        // default constructor
        ZooRecord();

        /**
        parameterized constructor
        @pre the input file is expected to be in CSV
        (comma separated value) format as:
        "animal_name,hair,feathers,eggs,milk,airborne,aquatic,predator,toothed,
        backbone,breathes,venomous,fins,legs,tail,domestic,catsize,class_type\n"
        @param input_file_name the name of the input file
        @post adds Animal objects to record as per the data in the input file
        **/
         ZooRecord(std::string input_file_name);

        /**
        @post displays all animals in record, one per line by calling animal's
        display method”
        **/
        void display(); 
};

#endif