Question

问题是

“创建一个指向Reader对象的至少四个指针的数组。使用New运算符可以创建指向派生类对象的至少三个指针，并将它们分配给数组”

The reader is the base class. The fantasyReader, horrorReader, misteryReader, and scienceReader are derived class.

我必须阅读Reader.txt

"""""""""""contents""""""""""""
David
0   <-Mystery category
John
1   <-Horror category
Mark
2   <-Science category
Sarah
3   <-fantasyReader
"""""""""""""""end"""""""""""""""""""

我拥有的

enum {HORROR, MYSTERY, SICENCE, FANTASY}; 

int main(void)
{
    Reader *obj[10];

    ifstream reader_file;

    int category =0; 
    string name; 
    string number; 
    int counter = 0;
    if(reader_file.is_open())
    {

        while( getline(reader_file, name,  
 ) && 
                getline(reader_file, number,  
 ))
        { 
            switch(category)
            {
                case FANTASY:
                    obj[counter++] = new fantasyReader(name);
                    break;
                case MYSTERY: 
                    obj[counter++] = new mysteryReader(name);
                    break
                case HORROR:
                    obj[counter++] = new horrorReader(name);
                    break;
                case SCIENCE:
                    obj[counter++] = new scienceReader(name);
                    break;
            }
        }
    }
}

我不确定我的代码是否回答了上面的问题。

Answer 1

您的问题是读取字符串数据（字符），但枚举值对应于整数。尝试：

category = atoi (number.c_str());

switch(category) {
      ...
}

另外，不要忘记打开和关闭文件：

reader_file.open ("readers.txt", ifstream::in);
...
reader_file.close();

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