OCR GCSE Computer Science Computational thinking, algorithms and programming June 2023 question paper J277/02

The table contains four statements about programming languages.

Tick (✓) one box in each row to identify whether each statement describes a low-level programming language or a high-level programming language.

The variables num1 and num2 store integers.

Write pseudocode to add the integers stored in num1 and num2. Store the result in a variable with the identifier total

Three incomplete pseudocode algorithms are given with a description of the purpose of each algorithm.

Write the missing arithmetic operator for each algorithm.

Outputting 12 to the power of 2.

Working out if a number is odd or even.

number = 53 if number ……………… 2 == 0 then print("Even number") else print("Odd number")

endif

Finding the difference between two measurements.

measurement1 = 300 measurement2 = 100

difference = measurement1 ……………… measurement2

Read the following pseudocode algorithm:

01 start = 3 02 do 03 print(start) 04 start = start - 1 05 until start == -1 06 print("Finished")

Complete the following trace table for the given algorithm.

This pseudocode algorithm totals all the numbers in the 0-indexed array scores

01 total = 0 02 for scoreCount = 1 to scores.length – 1 03 scores[scoreCount] = total + total 04 next scoreCount 05 print(total)

The function length returns the number of elements in the array.

The algorithm contains several errors.

Two types of errors in a program are syntax and logic errors.

State what is meant by a syntax error and a logic error.

Identify two logic errors in the pseudocode algorithm.

Write the refined line to correct each error.

Error 1 line number........

Error 2 line number........

An insertion sort is one type of sorting algorithm.

A student has written a pseudocode algorithm to perform an insertion sort on a 1D array names

names = ["Kareem", "Sarah", "Zac", "Sundip", "Anika"] for count = 1 to names.length – 1 pos = count while (pos > 0 and names[pos] < names[pos – 1]) temp = names[pos] names[pos] = names[pos – 1] names[pos – 1] = temp pos = pos – 1 endwhile next count

Describe the purpose of the variable temp in the insertion sort pseudocode algorithm.

An insertion sort contains a nested loop; a loop within a loop. In this pseudocode algorithm the outer loop is a count-controlled loop and the inner loop is a condition-controlled loop.

Explain why the inner loop needs to be a condition-controlled loop.

A bubble sort is another type of sorting algorithm.

Describe one difference between an insertion sort and a bubble sort.

Describe two similarities between an insertion sort and a bubble sort.

Draw a logic diagram for the floodlight.

Identify the logic gates for truth table 1 and truth table 2.

Charlie is developing an adding game. The rules of the game are:

• the player is asked 3 addition questions

• each question asks the player to add together two random whole numbers between 1 and 10 inclusive

• if the player gets the correct answer, 1 is added to their score

• at the end of the game their score is displayed.

Charlie has been told that the game will need to be tested before giving it to the players.

Explain why programs should be tested before use.

Complete the table by naming and describing one type of test that should be used on Charlie's program before releasing it.

Complete the table by identifying and describing two features of an IDE that can be used when testing a program.

Validating inputs can reduce errors when a program is being run.

Identify two methods of validation and explain how they can be used on this game.

Validation method 1........

Validation method 2........

Write an algorithm to play this game. The rules are repeated from the start of the question here:

• the player is asked 3 addition questions

• each question asks the player to add together two random whole numbers between 1 and 10 inclusive

• if the player gets the correct answer, 1 is added to their score

• at the end of the game their score is displayed.

OCR Security Services is a company that installs intruder alarm systems in commercial buildings.

The systems use a computer that is connected to the door sensors and window sensors.

The following data is stored in the system:

Below is a table showing some variables within the program.

Tick (✓) one box in each row to identify the most appropriate data type for each variable.

The alarm has an algorithm that decides whether to sound the alarm by checking the data that is stored in the following three variables.

• SystemArmed

• DoorSensorActive

• WindowSensorActive

The alarm will only sound when the alarm has been activated and one or both of the door and window sensors are activated. When the system needs to sound the alarm it calls the pre-written procedure SoundAlarm()

Write a program that checks the data in the variables and calls SoundAlarm() when appropriate.

You must use either:

• OCR Exam Reference Language, or

• A high-level programming language that you have studied.

Give the line number where there is concatenation.

Give the identifier of a variable used in the program.

Identify the data type of the data returned by the function CheckSensorCode()

Give the line number that contains a function call.

Identify two programming constructs that have been used in the program.

The alarm system has a log that stores a record each time a sensor is triggered. This is called an event. The record format is given in the table:

The log is stored in a database table called events. The current contents of events is shown:

Write an SQL statement to display the sensor IDs of the door sensors that have been triggered for more than 20 seconds.

A program written in a high-level language is used to access the data from the database. This program has a procedure, SaveLogs(), that stores the data to an external text file.

The procedure SaveLogs():

• takes the string of data to be stored to the text file as a parameter

• takes the filename of the text file as a parameter

• stores the string of data to the text file.

Write the procedure SaveLogs()

You must use either:

• OCR Exam Reference Language, or

• A high-level programming language that you have studied.

OCR Security Services need to identify the total number of seconds the sensors have been activated on a specific date.

The data from the database table events is imported into the program written in a high-level programming language.

The program stores the data in a two-dimensional (2D) string array with the identifier arrayEvents

The data to be stored is shown in the table.

In this table, the value of events[1, 1] contains "MS1".

An array can only store data of one data type. Any non-string data must be converted to a string before storing in the array.

Identify the process that converts integer data to string data.

Write a program that:

• asks the user to input a date

• totals the number of seconds sensors have been activated on the date input

• outputs the calculated total in an appropriate message including the date, for example: Sensors were activated for 40 seconds on 05/02/2023

You must use either:

• OCR Exam Reference Language, or

• A high-level programming language that you have studied.