Programming Concepts (Cambridge (CIE) IGCSE Computer Science)

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.

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

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
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

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