In the second step of the category partition technique, the goal is
to Identify Categories. Where categories are
characteristics of each input element. So
let me illustrate what that means using an example. And to do
that I'm going to use again the example of the split program, as
we are already familiar with it and we kind of already played
with it. When we were talking about the generic black box approach.
So let me bring back the program, and let me remind you
that what the program does is to take two inputs, a string and
the size, and it breaks down the string into chunks,
whose length is size. If we look at the split program
there are two input elements, str and size so we going to
identify categories for these two. So starting from str, what are
the interesting characteristics of the string? In, in this step
you're going to use your domain knowledge, your understanding of what a
string is, and for example we might identify the length of
the string and the content of the string as the two
main characteristics that we want to focus on. If we now
move our focus to size, the only characteristic I can really
think of for an integer is its value. So that's what
I'm going to mark here. So at the end of the step
what we have is that we have two categories. So two
interesting characteristics for the string input str, which are the length
and the content. And one category for the integer input size
which is its value. And notice that there's not only one solution.
So there's not only one possibility.
So that the specific characteristics that you
will identify are somehow subjective. But the
important point is that you identify characteristics
that are meaningful and they sort of cover the main aspects of the
inputs, which is the case for the
categories that we've identified in this example.