Making more robust and maintainable programs

Question 1

what are 2 defensive design methods?

Answer 1

data validation
anticipating misuse
verification

Question 2

what is data validation?

Answer 2

checking that user input meets certain criteria before processing it

Question 3

what are the 5 data validation checks and an example?

Answer 3

type check - strings, int
range check - 1 to 10
presence check- required fields
format check - dd/mm/yyyy
length check - longer than 10 characters

Question 4

what are the 3 benefits of data validation?

Answer 4

• more robust
• more user friendly
• prevent further errors in the algorithms

Question 5

what are 4 examples of anticipating misuse and a way to prevent each?

Answer 5

dividing by zero - check before calculations if variables are zero
communication error - failing to connect to a server, having a cancel request button
printer/peripheral error - always have a reprint option
disk errors - checking files and data before using them for processing

Question 6

give 3 ways to make a program for verified

Answer 6

username and password
password recovery
encryption
Captcha
defend against SQL injections

Question 7

why is keeping a program maintainable important

Answer 7

so that it can be understood and edited quickly by you or others

Question 8

what are 4 methods to maintain a program?

Answer 8

use comments - to explain or section out pieces of code
leave gaps - to make it easier to read and more organised
use indentation - for increased readability
use descriptive variables - so it is easier to tell what they do
use functions - to structure code
use constants