Question

Note: I’m using Visual Studio 2010.

There are two important classes here, Date and Directory.

class Date
{
private:
    int month, day, year;
public:
    Date();
    Date(int month, int day, int year);
};

class Directory : public [Superclass]
{
private:
    File* fileContents[50];
    Directory* dirContents[5];
public:
    Directory();
    Directory(char* name, 
        long size, 
        Date dateCreated, 
        Date dateModified,
        Date dateAccessed,
        int attributes);
};

I defined the constructors farther down – the Date constructor works just like you think it does. Now, I’m really new to C++, so I can’t even comprehend the error messages I’m getting. If I try to use the default constructor for Directory, I get this error message:

error LNK2019: unresolved external symbol "class Directory __cdecl d(void)" (?d@@YA?AVDirectory@@XZ) referenced in function _main

If I try to make it by using 3 Date objects, with this code:

int main()
{
    Date d1();
    Date d2();
    Date d3();
    Directory d("Hello", 12, d1, d2, d3, 0);
    cout << d;
}

These are my error messages:

error C2664: 'Directory::Directory(char *,long,Date,Date,Date,int)' : cannot convert parameter 3 from 'Date (__cdecl *)(void)' to 'Date'

IntelliSense: no instance of constructor "Directory::Directory" matches the argument list

EDIT: So, in a continuing effort to make zero sense to me, VS has decided to compile my program fine when the three Date arguments are created with Date da[3] and the arguments for the constructor are ("Hello", 12, d[0], d[1], d[2], 0).

Answer 1

According to the standard

An object whose initializer is an empty set of parentheses, i.e., (),
shall be value-initialized.

[Note: since () is not permitted by the syntax for initializer,

X a ();

is not the declaration of an object of class X, but the
declaration of a function taking no argument and returning an X. The
form () is permitted in certain other initialization contexts (5.3.4,
5.2.3, 12.6.2). —end note ]

So, you need to change your declarations as follows

int main()
{
    Date d1;
    Date d2;
    Date d3;
    Directory d("Hello", 12, d1, d2, d3, 0);
    cout << d;
}