Unit 8 Logic and Languages (2.3 Producing Robust Programs)

Question 1

What is defensive design?

Answer 1

Creating programs that can handle unexpected or erroneous data and/or inputs by anticipating misuse.

Question 2

How is defensive design put into place by programers?

Answer 2

they will try to:
* use input validation & authentication
* anticipate how users might misuse their program, then attempt to prevent this
* ensure their code is well maintained
* reduce the number of errors in the code throught testing

Question 3

What is anticipating misuse?

Answer 3

designing a system, predicting how users can act in an unintended or malicious way and minimising this

Question 4

What is authentication?

Answer 4

the process of determining the identity of a user

Question 5

What is input validation?

Answer 5

the process of checking that the data entered by a user is appropriate for its use, so that it can be correctly processed without any errors

Question 6

What are the (3) types of input validation?

Answer 6

• presence check
• range check
• length check

Question 7

What is a presence check?

Answer 7

checks that data has been entered and not blank.

Question 8

What is a range check?

Answer 8

checks that an input falls within the required range.

Question 9

What is a length check?

Answer 9

checks a specified number of characters have been entered.

Question 10

Give a python example of presence check

Answer 10

name = input(“Enter your name”)
if name == “”:
print(“Invalid”)

Question 11

Give a python example of range check

Answer 11

num = int(input(“Enter a number less than 10”))
if num >= 10:
print(“Too large!”)

Question 12

Give a python example of length check

Answer 12

password = input(“Enter a password, minimum 8 characters.”)
if len(password) < 8:
print(“Password too short!”)

Question 13

What is maintaining programs?

Question 14

What are the (4) ways of maintaining programs?

Answer 14

• sub programs
• naming conventions
• indentation
• commenting