Problem with creating array of pointers and assigning

Question

The problem was

"create an array of at leat four pointers to Reader object. Use the New operator to create at leat four pointers to derived class objects and assign them to the array"

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

I have to read from Reader.txt

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

What I have

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, '\n') && 
                getline(reader_file, number, '\n'))
        { 
            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;
            }
        }
    }
}

Im not sure if my codes are answering the question above.

Please remove all HTML tags from your question. To format the code, select it in the editor and hit the {} button. — user2100815
– user2100815, Commented May 29, 2011 at 10:03
@newb: there was a missing ; in your code (after counter = 0). — Mat
– Mat, Commented May 29, 2011 at 10:13
Looks fine to me though I haven't tested it. You just have to open the file (using reader_file.open() first) :D — iolo
– iolo, Commented May 29, 2011 at 10:16

Zaur Nasibov · Accepted Answer · 2011-05-29 11:02:37Z

2

Your problem is that you read string data (chars) but the enumeration values correspond to integers. Try:

category = atoi (number.c_str());

switch(category) {
      ...
}

Also, don't forget to open and close the file:

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

edited May 29, 2011 at 11:02

answered May 29, 2011 at 10:15

Zaur Nasibov

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2 Comments

Zaur Nasibov Over a year ago

Yep, atoi(). number is char*, atoi converts char* to int. Or one can just use boost:lexical_cast ;)

johnsyweb Over a year ago

Nasibov: No. number is declared as string, presumably the one inside namespace std. This is not char*.

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