2.3

Question 1

input validation

Answer 1

checking data input by the user meets criteria

Question 2

types of input validation

Answer 2

• type check, e.g. integer, real, string
• range check, e.g. blank inputs
• presence check, e.g. reject blank inputs
• format check, e.g. postcode
• length check, e.g. password

Question 3

advantages of input validation

Answer 3

• a programmer can make their program more robust, user friendly

Question 4

types errors that can occur in code

Answer 4

anticipation misuse
communication error
printer error
disks error

Question 5

anticipating misuse

Answer 5

• e.g. dividing a number by 0
• the ALU cannot compute said division
• a programmer should always check that a variable is not 0 before attempting a division

Question 6

communication error

Answer 6

• online systems require connections to host servers
• if this connection is dropped, unable to be established or the server is overloaded, it can cause the program to crash or hang when loading data

Question 7

printer error

Answer 7

• if a program outputs a hardcopy, the printer may run out of ink or jam
• the programmer should not assume that an output to a printer was successful and always have options to reprint reports o receipts

Question 8

disk errors

Answer 8

• programs that read and write to files need to handle many types of exceptions including:
  the file/folder not being found
  the disk being out of space
  the data in the file being corrupt
  the end of the file being reached

Question 9

authentication

Answer 9

• e.g using passwords to access systems

Question 10

dangers of not encrypting of data files and how to protect against it

Answer 10

• online bots can submit data automatically to online forms
• this can be protected against using software such as recaptcha that verifies if the user is human

Question 11

how to maintain code

Answer 11

• use comments to separate code
• use comments to explain parts of code
• indentation of code
• use procedures and functions

Question 12

reasons for testing code

Answer 12

• to ensure there are no errors in code
• check that the program has good performance
• ensure that unauthorised access is prevented
• check the program meets the requirements

Question 13

iterative testing

Answer 13

• each new module is tested as it is written
• program branches are checked for functionality
• checking new modules do not introduce new errors in existing code

Question 14

final testing

Answer 14

• testing that all modules work together
• testing the program produces the requires results with normal, boundary, invalid and erroneous data
• checking the program meets the requirements with real data

Question 15

syntax error

Answer 15

the rules of the language have been broken

Question 16

types of data test inputs

Answer 16

normal inputs
boundary inputs
invalid inputs
erroneous inputs

Question 17

normal inputs

Answer 17

• data which should be accepted by a program without causing errors

Question 18

boundary inputs

Answer 18

• data of the correct type which is on the edge of accepted validation boundaries

Question 19

invalid inputs

Answer 19

• data of the correct type but outside accepted validation checks

Question 20

erroneous inputs

Answer 20

• data of the incorrect type which should be rejected by a computer system

Question 21

ways to make an algorithm more robust

Answer 21

• writing code which anticipates a range of possible inputs
• those inputs could be invalid data or erroneous
• making sure “bad” data does not crash the program
• making sure prompts to the user are descriptive and helpful