2.3. Programming
A subsection of Computer Science, 9608, through 2. Fundamental Problem-solving and Programming Skills
Listing 5 of 5 questions
Consider the following user-defined data type: TYPE LibraryBookRecord DECLARE ISBN : INTEGER DECLARE Title : STRING ENDTYPE Write a pseudocode statement to declare a variable, Book, of type LibraryBookRecord. Write a pseudocode statement that assigns ‘Dune’ to the Title of Book. The user-defined data type LibraryBookRecord needs to be modified by adding the following fields: • a field called Genre which can take two values, fiction or non-fiction • a field called NumberOfLoans which can be an integer value in the range 1 to 99 Write the updated version of LibraryBookRecord. A pointer is a variable that stores the address of a variable of a particular type. Consider the code on page 3, which uses the following identifiers: Identifier Data type Description IntPointer ^INTEGER pointer to an integer IntVar INTEGER an integer variable Temp1 INTEGER an integer variable Temp2 INTEGER an integer variable IntVar // assigns the value 57 to the integer // variable IntVar IntPointer @IntVar // assigns to IntPointer the address of the // integer variable IntVar Temp2 IntPointer^ // assigns to variable Temp2 the value at an // address pointed at by IntPointer IntPointer^ Temp1 // assigns the value in the variable Temp1 to // the memory location pointed at by IntPointer The four assignment statements are executed. The diagram shows the memory contents after execution. Variable Memory address Contents . . . IntVar . . . IntPointer . . . Temp1 Temp2 . . . Use the diagram to state the current values of the following expressions: @Temp2 IntPointer IntPointer^ IntPointer^ = Temp2 + 6 Write pseudocode statements that will achieve the following: Assign the value 22 to the variable Temp2. Place the address of Temp1 in IntPointer. Copy the value in Temp2 into the memory location currently pointed at by IntPointer.
9608_s17_qp_31
THEORY
2017
Paper 3, Variant 1
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Consider the following pseudocode user-defined data type: TYPE MyContactDetail DECLARE Name : STRING DECLARE HouseNumber : INTEGER ENDTYPE Write a pseudocode statement to declare a variable, NewFriend, of type MyContactDetail. Write a pseudocode statement that assigns 129 to the HouseNumber of NewFriend. The user-defined data type MyContactDetail needs to be modified by: • adding a field called Area which can take three values, uptown, downtown or midtown • amending the field HouseNumber so that house numbers can only be in the range 1 to 499. Write the updated version of MyContactDetail. A pointer is a variable that stores the address of a variable of a particular type. Consider the pseudocode on page 3, which uses the following identifiers: Identifier Data type Description IPointer ^INTEGER pointer to an integer Sum INTEGER an integer variable MyInt1 INTEGER an integer variable MyInt2 INTEGER an integer variable Sum // assigns the value 91 to the integer variable Sum IPointer @Sum // assigns to IPointer the address of the // integer variable Sum MyInt1 IPointer^ // assigns to variable MyInt1 the value at an // address pointed at by IPointer IPointer^ MyInt2 // assigns the value in the variable MyInt2 to // the memory location pointed at by IPointer The four assignment statements are executed. The diagram shows the memory contents after execution. Variable Memory Address Contents . . . IPointer . . . Sum . . . MyInt1 MyInt2 . . . Use the diagram to state the current values of the following expressions: IPointer IPointer^ @MyInt1 IPointer^ = MyInt2 Write pseudocode statements that will achieve the following: Place the address of MyInt2 in IPointer. Assign the value 33 to the variable MyInt1. Copy the value in MyInt2 into the memory location currently pointed at by IPointer.
9608_s17_qp_32
THEORY
2017
Paper 3, Variant 2
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Consider the following user-defined data type: TYPE LibraryBookRecord DECLARE ISBN : INTEGER DECLARE Title : STRING ENDTYPE Write a pseudocode statement to declare a variable, Book, of type LibraryBookRecord. Write a pseudocode statement that assigns ‘Dune’ to the Title of Book. The user-defined data type LibraryBookRecord needs to be modified by adding the following fields: • a field called Genre which can take two values, fiction or non-fiction • a field called NumberOfLoans which can be an integer value in the range 1 to 99 Write the updated version of LibraryBookRecord. A pointer is a variable that stores the address of a variable of a particular type. Consider the code on page 3, which uses the following identifiers: Identifier Data type Description IntPointer ^INTEGER pointer to an integer IntVar INTEGER an integer variable Temp1 INTEGER an integer variable Temp2 INTEGER an integer variable IntVar // assigns the value 57 to the integer // variable IntVar IntPointer @IntVar // assigns to IntPointer the address of the // integer variable IntVar Temp2 IntPointer^ // assigns to variable Temp2 the value at an // address pointed at by IntPointer IntPointer^ Temp1 // assigns the value in the variable Temp1 to // the memory location pointed at by IntPointer The four assignment statements are executed. The diagram shows the memory contents after execution. Variable Memory address Contents . . . IntVar . . . IntPointer . . . Temp1 Temp2 . . . Use the diagram to state the current values of the following expressions: @Temp2 IntPointer IntPointer^ IntPointer^ = Temp2 + 6 Write pseudocode statements that will achieve the following: Assign the value 22 to the variable Temp2. Place the address of Temp1 in IntPointer. Copy the value in Temp2 into the memory location currently pointed at by IntPointer.
9608_s17_qp_33
THEORY
2017
Paper 3, Variant 3
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The following syntax diagrams for a particular programming language show the syntax of: • an unsigned number • an unsigned integer • a digit. Unsigned integer Unsigned number . Unsigned integer Digit Unsigned integer Digit Explain why 32 is a valid unsigned integer. Explain why 32.5 is a valid unsigned number. Complete the Backus-Naur Form (BNF) for the syntax diagrams shown. ::= ::= ::= The format of an unsigned number is amended to include numbers with possible exponents. If an unsigned number has an exponent, then the exponent part: • will start with an ‘E’ • be followed by an optional ‘+’ or ‘−’ sign • and be completed by an unsigned integer. Examples of unsigned numbers with exponents include: 3E2, 3E+3, 3E−32, 3.45E−2 Redraw the syntax diagram for unsigned number to include numbers that might have exponents. Use your syntax diagram from part to write the BNF for an unsigned number to include numbers with exponents. ::=
9608_w17_qp_32
THEORY
2017
Paper 3, Variant 2
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Questions Discovered
5