Computational Constructs

Question 1

What does declarative programming focus on?

Answer 1

Defining what a program should achieve rather than defining the method of achieving the desired output

Question 2

What does Imperative Programs define?

Answer 2

Exactly the steps that a computer will execute to achieve a specific result

Question 3

What do programs in Prolog consist of?

Answer 3

Facts and Rules

Question 4

What is a knowledge base?

Answer 4

Combination of the facts and rules in prolog

Question 5

What is Recursion?

Answer 5

A programming technique where a sub-program repeatedly calls itself

Question 6

In what type of programming languages is recursion used?

Answer 6

Declarative and Imperative Programming Styles

Question 7

What is passing by reference?

Answer 7

Passing the real copy of the parameter, changes to this parameter will be proper changes

Question 8

What is passing by value?

Answer 8

Any changes to the parameter will not be carried onto the real value

Question 9

Write the pseudocode for the Fibonacci sequence

Answer 9

def Fibonacci(n):
If n < 2:
return n
else 
return Fibonacci(n-1) + Fibonacci(n-2)

Question 10

Give some advantages of recursion

Answer 10

• It is a unique way of implementing a variable number of nested
  loops.
• Prevents repeating of code

Question 11

Give some disadvantages of recursion

Answer 11

• Recursion uses more memory than iteration and looping
• Recursive methods will often throw a Stack Overflow Exception error
  when processing big sets of data

Question 12

What are the operations that can performed on a sequential file?

Answer 12

• Write data
• Read data
• Append

Question 13

What is a sequential file identified by?

Answer 13

Identified by a path and a filename

Question 14

Describe a sequential file

Answer 14

• Identified by a path and a filename
• Reading from the beginning
• Cannot be written and read to at the same time
• If file does not exist, must be created first

Question 15

What is the difference between append and read/write functions for sequential file?

Answer 15

Append allows data to be added to the file without it being read into memory first

Question 16

Write pseudocode for writing (a set of string values)to a new sequential text
file from an array

Answer 16

Procedure writeFile(name):
DECLARE myFile INITIALLY "N://myFile.txt"
CREATE myFile
OPEN myFile
FOR counter FROM 0 to End of Array DO
SEND names[counter] to myFile
END FOR
CLOSE myFile
END Procedure

Question 17

Write pseudocode for reading (a set of string values) from a sequential text file into
an array

Answer 17

PROCEDURE ReadFile(name)
DECLARE myFile INITIALLY "N://myFile.txt"
OPEN myFile
FOR counter FROM 0 to End of File DO
Receive names[counter] from myFile
END FOR
CLOSE myFile
END PROCEDURE

Question 18

Describe a random file

Answer 18

A file which stores data in a way which allows it to be retrieved from any place in the file without needing to read through the entire file
Data is indexed in a way which allows each item to be uniquely identified

Question 19

What are random files frequently used to store?

Answer 19

Records

Question 20

Give three advantages to random files?

Answer 20

• Fast access to data since position of any item can be calculated from it’s index
• Data items can be accessed individually instead of having to read the entire file
• Random files can be read and written to simultaneously