2.3.1 Flashcards
what is defensive design?
the practice of anticipating every possible way that a user could misuse a system or device
a defensive design has not been good enough when:
-the program crashes
-the program behaves in an unintended fashion
-data security has been compromised
what does defensive design anticipate?
it anticipates misuse and uses authentication
what’s the first part of defensive design?
to decide what type of user interface to use: command line interface, graphical interface, menu driven interface
what’s the second part of defensive design?
considering how data is entered- using widgets is a way of limiting data entries and preventing entry errors
what’s the third part of defensive design?
when data is entered into a program it is important that it is valid in order for the program to operate correctly
validation
check made by a computer to ensure that the data entered is sensible or reasonable
what are the different types of validation checks?
-presence check
-range check
-type check
-format check
-lookup check
-contingencies
presence check
makes sure the data has been entered in a particular field
range check
ensures the data is within a certain limit
type check
ensures the data is in the correct data type
format check
ensures the data entered matches a particular pattern
lookup check
checks to see if the data exists in a list
contingencies
unexpected events, this could include: invalid input of data, file missing ect.
global
the variable can be used outside a function
what can be used to increase the maintainability of a program?
-sub programs
-naming conventions
-indentation
-commenting
why is maintenance of a business needed?
-errors are found in the software
-a security loophole could be found
-customer would like improvements
-external factors could change
what needs to happen to carry out maintenance on a code?
-the programmer needs to understand the code
identifier
a word chosen by the programmer to identify the constant or subroutine (must be unique and have no spaces)
comments
explain what each part of the code does and makes it easier to understand what they wrote and why
constant
if a value does not need to change when a program is running it can be a constant
indentation
helps to show a programmer where a block of code finishes, important for understanding how a code works
white space
leaving a line gap between sections of code makes it more readable
subprograms
makes programs more readable as the detail of each subroutine can be ignored when looking at the whole program
