Programming Concepts (Cambridge International IGCSE Computer Science): Exam Questions

Four pseudocode descriptions and five pseudocode statements are shown.

Draw a line to link each pseudocode description to the most appropriate pseudocode statement.

Some pseudocode statements will not be used

Tick (✓) one box to show the named section of a program that performs a specific task.

A function is declared using pseudocode.

FUNCTION ConvertToCm(Inches: REAL) RETURNS REAL RETURN Inches * 2.4 ENDFUNCTION

Tick (✓) one box which accurately describes the use of the variable Inches

A database table, 2018MOV, is used to keep a record of movie details

Complete the table to identify the most appropriate data type for each field based on the data shown in the database table, 2018MOV.

The variables X, Y and Z are used to store data in a program:

• X stores a string
• Y stores a position in the string (e.g. 2)
• Z stores the number of characters in the string.

Write pseudocode statements to declare the variables X, Y and Z.

Four programming concepts and four descriptions are shown.

Draw one line to connect each programming concept to the most appropriate description

Tick (✓) one box in each row to identify the most appropriate data type for each description. Only one tick (✓) per column.

An algorithm has been written in pseudocode to calculate a check digit for a four-digit number. The algorithm then outputs the five-digit number including the check digit. The algorithm stops when –1 is input as the fourth digit.

01 Flag FALSE 02 REPEAT 03 Total 0 04 FOR Counter 1 TO 4 05 OUTPUT "Enter a digit ", Counter 06 INPUT Number[Counter] 07 Total Total + Number * Counter 08 IF Number[Counter] = 0 09 THEN 10 Flag TRUE 11 ENDIF 12 NEXT Counter 13 IF NOT Flag 14 THEN 15 Number[5] MOD(Total, 10) 16 FOR Counter 0 TO 5 17 OUTPUT Number[Counter] 18 NEXT 19 ENDIF 20 UNTIL Flag

Give the line number(s) for the statements showing:

• Totalling
• Count-controlled loop
• Post-condition loop

The variables P and Q are used to store data in a program. P stores a string. Q stores a character.

Write pseudocode statements to declare the variables P and Q, store "The world" in P and store 'W' in Q

Describe the difference between a local variable and a global variable.

Write the pseudocode to use a procedure named Average that passes the values 25 and 50 to the procedure.

A function LENGTH(X) finds the length of a string X and a function SUBSTRING(X,Y,Z) finds a substring of X starting at position Y and Z characters long. The first character in the string is position 1.

P ← "Computer Science"

Write a pseudocode statement to extract the word Computer from P and store it in the variable F.

Explain the difference between a WHILE … DO … ENDWHILE and a REPEAT … UNTIL loop

B ← FALSE INPUT Num FOR Counter ← 1 TO 12 IF A[Counter] = Num THEN B ← TRUE ENDIF NEXT Counter

Explain the purpose of the library routines DIV and ROUND.

State two features that should be included to create a maintainable program.

Give a reason why each feature should be used.

The function LENGTH(Phrase) calculates the length of a string Phrase

The string "*The beginning is the most important part" is stored in *Phrase

State the output of the pseudocode statements:

• OUTPUT LENGTH(Phrase)
• OUTPUT UCASE(Phrase)

The variables P and Q are used to store data in a program. P stores a string. Q stores a character.

Write a pseudocode algorithm to:

• convert P to upper case
• find the position of Q in the string P (the first character in this string is in position 1)
• store the position of Q in the variable Position

Four descriptions of programming concepts and five programming concepts are shown.

Draw one line to link each description to the most appropriate programming concept.

Not all programming concepts will be used.

Outline the role of procedures and functions in creating a program that is easier to maintain.

State what is meant by the data types integer and real.

Give an example of each.

Write the pseudocode statements to perform this task:

• Accept the input of a whole number from 1 to 4 inclusive • Use a CASE statement to:  ○ output the number (1 to 4 inclusive) that was entered  ○ output the word “ERROR” if a 1 to 4 inclusive number was not entered

A function LENGTH(X) finds the length of a string X and a function SUBSTRING(X,Y,Z) finds a substring of X starting at position Y and Z characters long. The first character in the string is position 1.

Q ← "Programming Languages"

Write a pseudocode statement to extract the word Languages from Q and store it in the variable G.

Write the pseudocode statements to perform this task:

• Accept the input of two whole numbers: a grade (1 to 5 inclusive) and a subject code (10, 20, 30, or 40)

• Use nested selection statements to:

○ If the grade is valid (1 to 5), use a CASE statement to check the subject code:

• If subject code is 10: output "Mathematics - Grade " followed by the grade
• If subject code is 20: output "Science - Grade " followed by the grade
• If subject code is 30: output "English - Grade " followed by the grade
• If subject code is 40: output "History - Grade " followed by the grade
• If subject code is invalid: output "INVALID SUBJECT"

○ If the grade is not valid (not 1 to 5 inclusive), output "INVALID GRADE"

Using a single loop, write an algorithm in pseudocode to output 50 names that have been stored in the array, Name[]

The function LENGTH(Phrase) calculates the length of a string Phrase

Write the pseudocode statements to:

• store the string "The beginning is the most important part" in Phrase.
• calculate and output the length of the string
• output the string in upper case.

A program needs to make sure the value input for a measurement meets the following rules:

• the value is a positive number
• a value is always input
• the value is less than 1000.

The program needs editing to include a double entry check for the value input.

The input value needs to be stored in the variable Measurement Write pseudocode to perform the double entry check until a successful input is made.

An algorithm has been written in pseudocode to calculate a check digit for a four-digit number. The algorithm then outputs the five-digit number including the check digit. The algorithm stops when –1 is input as the fourth digit.

01 Flag FALSE 02 REPEAT 03 Total 0 04 FOR Counter 1 TO 4 05 OUTPUT "Enter a digit ", Counter 06 INPUT Number[Counter] 07 Total Total + Number * Counter 08 IF Number[Counter] = 0 09 THEN equation``10 Flag $\leftarrow$TRUE 11 ENDIF 12 NEXT Counter 13 IF NOT Flag 14 THEN 15 Number[5] MOD(Total, 10) 16 FOR Counter 0 TO 5 17 OUTPUT Number[Counter] 18 NEXT 19 ENDIF 20 UNTIL Flag

The algorithm does not check that each input is a single digit. Identify the place in the algorithm where this check should occur.

Write pseudocode for this check. Your pseudocode must make sure that the input is a single digit and checks for –1

A function LENGTH(X) finds the length of a string X and a function SUBSTRING(X,Y,Z) finds a substring ofXstarting at position Y and Z characters long. The first character in the string is position 1.

Show the value of the variable after each pseudocode statement has been executed.

01 P ← "Computer Science"

02 Q ← LENGTH(P)

03 R ← SUBSTRING(P,10,7)

04 S ← LENGTH(R)

05 T ← SUBSTRING(R,1,3)