programming concepts (paper 2)

Question 1

what happens to data used in a program

Answer 1

it is stored in memory locations while the program is running

Question 2

what is a variable

Answer 2

a data item held in memory which may change value during program execution

Question 3

what is a variable referred to by

Answer 3

its identifier

Question 4

what are the different types of data variable can be

Answer 4

• integer (5, -297)
• real (3.12, 9.999)
• char (A, @, $, 4)
• string (Yes, Hello world)
• boolean (TRUE, FALSE)

Question 5

what is a constant

Answer 5

a value that cannot change during the execution of hte program (CONSTANT VAT <- 0.2)

Question 6

what is the diifference between a variable and a constant

Answer 6

a variable can change during the program execution, a constant does not

Question 7

what is an input

Answer 7

when the user inputs data or a request into the program to get an output (INPUT Name)

Question 8

what is an output

Answer 8

it is used to output data on the screen after information has been processed by the user (OUTPUT “Area = “, Length * Width)

Question 9

what is a boolean expression

Answer 9

something which uss one or more logical operators and evalutes to either TRUE or FALSE

Question 10

what is a sequence control structure

Answer 10

when two or more statements are written and executed one after the other in sequence

Question 11

what is a selectrion control structure

Answer 11

comprises an IF or CASE statement and a logical expression (CASE OF… OTHERWISE… ENDCASE…, IF… THEN…)

Question 12

give an example of a nested if statement

Answer 12

IF Num1 >= Num2 AND Num1 >= Num3
THEN
OUTPUT Num1
ELSE
IF Num2 >= Num1 AND Num2 >= Num3
THEN
OUTPUT Num2
ELSE
OUTPUT Num3
ENDIF
ENDIF

Question 13

what does a case statement actually allow to happen

Answer 13

one of several brances of code to be executed depending on what data has been inputed by the user

Question 14

give me an example of a case statement

Answer 14

INPUT MemberType
CASE OF MemberType
“Junior” : EntryFee <- 2.0
“Senior” : EntryFee <- 3.0
“Special” : EntryFee <- 0.0
OTHERWISE OUTPUT “Invalid member type”
ENDCASE

Question 15

what does iteration mean

Answer 15

repetition

Question 16

what loop is count-controlled

Answer 16

FOR… NEXT

Question 17

give an example of a FOR.. NEXT loop nested

Answer 17

FOR Table <- 2 TO 10
FOR N <- 1 TO 10
Answer <- Table * N
OUTPUT Answer
NEXT N
NEXT Table

Question 18

what loop is condition controlled

Answer 18

WHILE… DO … ENDWHILE (pre-condition - checked at the start)
REPEAT… UNTIL (post-condition - checked at the end)

Question 19

Give an example of a WHILE… DO… ENDWHILE loop

Answer 19

Total <- 0
Days <- 0
INPUT Visitors
WHILE Visitors <> -1 DO
Total <- Total + Visitors
Days <- Days + 1
INPUT Visitors
ENDWHILE
Average <- Total / Days
OUTPUT “Average daily number of visitors:”
OUTPUT Average

Question 20

how is a string defined

Answer 20

as zero or more characters enclosed in quote marks (“”)

Question 21

what are the different string functions and what do that do

Answer 21

• LENGTH(“ “) = returns the number of characters (including spaces)
• LCASE(“ “) = makes everything in parameter lower case
• UCASE(“ “) = makes everything in parameter upper case
• SUBSTRING(“ “, Num, Num) = makes everything in the quote marks outputed between the two numbers

Question 22

what is a procedure

Answer 22

a named block of code, seperate from the main program, which can be called and executed using a statement like (CALL <procedure>)</procedure>

Question 23

what does a procedure do

Answer 23

• it does not return a value
• control is passed using the CALL statement with any parameters in brackets

Question 24

what is a function

Answer 24

a block of code which returns a value to a variable specific in the statement (eg you would have a function just for calculating the total of smt or the avergage)

Question 25

what are parameters

Answer 25

values passed to the subroutine, which are delcared in the parentheses within the call instruction

Question 26

what are functions and procedures essential in in the program life cycle

Answer 26

decomposition - breaking down a complex problem into smaller sub-problems and sub-tasks

Question 27

what is a local variable

Answer 27

a variable which is only recognised inside a subroutine, if you were to call it in the main program then you would recieve an error message

Question 28

what is a global variable

Answer 28

a variable which is recognised in the whole program, including all the subroutines

Question 29

what are the two library routines

Answer 29

• the ROUND function
• the random number generation function

Question 30

how would you write the round function in a psuedocode program

Answer 30

X <- 3.14159
Y <- ROUND(X, 2) //returns 3.14 in Y as it is 2dp

Question 31

how would you write the random interger function in a psudocode program

Answer 31

RANDOM() // generates a random float point number between 0 and 1

Question 32

what is an array

Answer 32

a data structure used to hold several elements of the same data type

Question 33

how do you declare a 1D array, use this example of an array of 10 student names

Answer 33

DECLARE StudentName : ARRAY[1:10] OF STRING

Question 34

how would you assign the name “Morris” to the third index of the array

Answer 34

StudentName[3] <- “Morris”

Question 35

how do you declare a 2D array, use this example of a table of Sales over 4 months and three different shops

Answer 35

DECLARE Sales : ARRAY[1:3, 1:4] OF INTEGER

Question 36

DECLARE Sales : ARRAY[1:3, 1:4] OF INTEGER
How many rows (horrizonal) are there in this array

Answer 36

3

Question 37

DECLARE Sales : ARRAY[1:3, 1:4] OF INTEGER
How many collumns (verticle) are there in this array

Answer 37

4

Question 38

how is data stored in a hard disk or SSD so that it can be written to

Answer 38

files

Question 39

what is the purpose of storing data in a file to be used by a program

Answer 39

because then the file can be read or written into in many different programs, without having to re-enter the data all over again

Question 40

what are the two different things you can do to a file

Answer 40

• read to it
• write to it

Question 41

how would you open a text file on members to write

Answer 41

OPENFILE MemberFile.txt FOR WRITE
INPUT MemberID, Surname, Firstname
WHILE MemberID <> “END” DO
MemberRecord <- MemberID + “,” + Surname + “,” + Firstname
WRITEFFILE MemberFile.txt, MemberRecord
INPUT MemberID, Surname, Firstname
ENDWHILE
CLOSEFILE MemberFile.txt

Question 42

how would you close a file

Answer 42

CLOSEFILE …..

Question 43

how would you open a text file to read

Answer 43

OPENFILE MemberFile.txt FOR READ

Question 44

how would you read to a file after opening it

Answer 44

READFILE MemberFile.txt, MemberRecord
WHILE NOT MemberFile.endOfFile DO
OUTPUT MemberRecord
READFILE MemberFile.txt, MemberRecord
ENDWHILE
CLOSEFILE MemberFile.txt