programming-for-dummies

138
Creating a User Interface
Sounds like a lot of work just to make a simple change? It is, and that’s why
loose coupling between subprograms is so important. Because programmers
can’t always be trusted to make sure their subprograms are loosely coupling,
OOP forces them to do it whether they like it or not.
Creating a User Interface
The three actions of most programs are
✦ Get data.
✦ Manipulate that data.
✦ Create a result.
A football-picking program takes in data about both teams, uses a formula to
predict a winner, and prints or displays its answer on-screen. A hotel reservation
program gets a request for a room from the user (hotel clerk), scans
its list of rooms for one that’s available and that matches the user’s criteria
(no smoking, two beds, and so on), and displays that result on-screen.
Basically, every program takes in data, calculates a result, and displays that
result. To accept data from the user and display a result back to the user
again, every program needs a user interface, as shown in Figure 1-9.
Figure 1-9:
The user
interface
accepts
data and
displays the
results of its
calculations
back to
the user.
User
Give data
Display new data
User
Interface
Give data
Return new data
Main
Program