Objects As Arguments

Now we can see how ENGLCON works. The distances dist1 and dist3 are created using the default constructor (the one that takes no arguments). The distance dist2 is created with the constructor that takes two arguments, and is initialized to the values passed in these arguments. A value is obtained for dist1 by calling the member function getdist(), which obtains values from the user.

Now we want to add dist1 and dist2 to obtain dist3. The function call in main(),

dist3.add_dist(dist1, dist2);

does this. The two distances to be added, dist1 and dist2, are supplied as arguments to add_dist(). The syntax for arguments that are objects is the same as that for arguments that are simple data types like int: The object name is supplied as the argument. Since add_dist() is a member function of the Distance class, it can access the private data in any object of class Distance supplied to it as an argument, using names like dist1.inches and dist2.feet.

Close examination of add_dist() emphasizes some important truths about member functions. A member function is always given access to the object for which it was called: the object connected to it with the dot operator. But it may be able to access other objects. In the following statement in ENGLCON, what objects can add_dist() access?