Array of objects from another class

I have no experience with C++ other than going through the FAQ to find
my answer but I'm stuck. I did a search on Google Books through
Deitel's C++ book but the preview is limited. I have bought Deitel's
book on C++ on Amazon but it hasn't been delivered yet. There's no
Barnes & Nobles within 50 miles from where we live and the localy
library isn't barren of computer books.

I'm trying to create a simple table in order to start learning C++,
something I can try hashing numbers or characters or strings into. I
don't know much about tables so it's possible I have the concept
wrong.

In my header file, I put the following, leaving out any directives to
save space:

class data {
        public:
                data(int);
                ~data(int);
        private:
                int item;
};

In my definitions file, my constructor is simple:

data::data(int x) {
               item = x;
}

I then built another class to create a table, a table consisting of an
array of data items so I can hash numbers or strings into them, but I
don't think I'm constructing it correctly:

Here's my class definition file for the table I want to create:

#include "data.h"

class data_table {
        public:
                data_table(int);
                ~data_table();
        private:
                data *data_entries; // pointer to an array of data
items.
                int table_size;
};

#include "data.h"

data_table::data_table(int size) {
        table_size = size;
        data_entries = new data[size]; // compiler error
        ...
        }

The warning I'm getting is: no matching function for call to
`data::data()'

I modified my data class definition to include an array, a pointer,
and a copy constructor, but I can't seem to get this to work.

I can stop the compiler errors if I change this

        data_entries = new data[size];

to this:

        data_entries = new data(size};

but then when I try to write code to access the data_entires array,
there's more compiler errors.

I know I should use a vector, but that's beyond me right now. Is
there a simple solution to this error? I'm sorry if this is an easy
question.