Problem solving, design, and programming

Question 1

What is a sub-routine?

Answer 1

It is a set of instructions that perform a frequently used operation in the sun-system of a program.

Question 2

What is top-down design?

Answer 2

Top-down design is a method of designing a computer system, in which the system is broken down into sub-systems, which are further broken down into sub-systems, until each subsystem performs just a single task.

Question 3

What are the advantages of using this type of design?

Answer 3

1. Division of labor - reduces design time
2. Accounts for differences in skills of programmers - everyone does not have to be proficient in everything.
3. Problems are broken down into manageable parts- easier to find a solution.

Question 4

What is a library routine?

Answer 4

It is a set of instructions to perform a task that is already available for use.

Question 5

What are the different types of test data?

Answer 5

Normal data - Which is accepted

Abnormal data - Rejected

Boundary data - Establishes what the smallest and largest data that are accepted are

Extreme data - Largest and smallest values that are accepted

Blank data - No data is given

Question 6

What is the difference between validation and verification?

Answer 6

Validation is checking data against a set of criteria to make sure that is correct. Verification is making sure that data has been copied/transferred correctly.

Question 7

What are some examples of validation checks? (include how to calculate check digit)

Answer 7

1. Character checks - check for invalid characters, eg. accents
2. Range checks - Does the data fall within the given range?
3. Length check - Does the data exceed the set length limit?
4. Format check - Is the data in the right format, eg. in image?
5. Type check - Is the data the valid type of data? Eg. when only alphabetical data is allowed.
6. Check digit:
7. Add all odd numbers
8. Add all even numbers and divide the result by 3.
9. Add result from 1 and 2 and divide it by 10
10. Take the remainder - is it is 0, use the above number, else subtract it from 10 to find the check digit

Question 8

What are some examples of verification checks? (include how to calculate check sum)

Answer 8

1. Double entry - Data is entered twice and checked for inconsistencies, eg. passwords
2. Visual check - User is asked if the data entered is correct
3. Parity checks - Even/odd parity to make sure that data is transmitted correctly
4. Checksum
5. Take the sum of the length of the binary data. If it is less then or equal to 255, this is the checksum. If it is greater than 255:
6. Divide the sum (X) by 255
7. Round it to the nearest whole number, A
8. B = 256 * A
9. Calculate X - B
10. 4 is the checksum

Question 9

How can you decide if a solution is effective?

Answer 9

These criteria can be applied when determining the effectiveness of a solution:

1. Does it carry out its function?
2. How quickly does it carry out its function? - The faster, the better.
3. Are there any risks associated with applying this solutions, for example security threats?