Sometimes you may want to declare a class and yet not know how to define all of the methods that belong to that class.
For example, you may want to declare a class called Writer and include in it a member method called write(). However, you don't know how to code write() because it is different for each type of Writer Device. Of course, you plan to handle this by deriving subclasses of Writer, such as Printer, Disk, Network and Console.
> Why use abstract classes at all? Why not just declare a class and
> then make sure you never instantiate any variables of that type?
...because compile time checks are far superior/efficient when compared to your code blowing up at run time. Languages which don't have the concept of Abstract classes baked in reply on hacks to achieve the same [e.g. Actionscript 3].
I have a 2d matrix with dimension (3, n) called A, I want to calculate the normalization and cross product of two arrays (b,z) (see the code please) for each column (for the first column, then the second one and so on).
the function that I created to find the ...
Write a C program that should create a 10 element array of random integers (0 to 9). The program should total all of the numbers in the odd positions of the array and compare them with the total of the numbers in the even positions of the array and indicate ...