Writing a complete array program: declare, fill and output

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Quick Questions

Shade in the A or B circle for each question.

1. Which order shows the correct pattern for a complete array program?

A FOR loop with OUTPUT, FOR loop with INPUT, DECLARE the array

B DECLARE the array, FOR loop with INPUT, FOR loop with OUTPUT

2. Which line correctly declares a 1D array to hold 5 student names?

A DECLARE StudentNames : ARRAY[1:5] OF INTEGER

B DECLARE StudentNames : ARRAY[1:5] OF STRING

3. Which loop correctly fills the Marks array with 5 values typed in by the user?

A FOR Index ← 1 TO 5 INPUT Marks[Index] NEXT Index

B FOR Index ← 1 TO 5 OUTPUT Marks[Index] NEXT Index

4. A program has DECLARE Marks : ARRAY[1:30] OF INTEGER. Which loop header visits every element?

A FOR Index ← 1 TO 30

B FOR Index ← 1 TO 31

5. Which is the best way to write the OUTPUT loop body for the array StudentNames?

A OUTPUT StudentNames[Index]

B OUTPUT StudentNames

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1DECLARE Marks : ARRAY[1:5] OF INTEGER		AFOR Row ← 1 TO 3 FOR Col ← 1 TO 4 INPUT Grid[Row, Col] NEXT Col NEXT Row
2FOR Index ← 1 TO 5 INPUT Marks[Index] NEXT Index		BFOR Index ← 1 TO 5 OUTPUT Names[Index], Marks[Index] NEXT Index
3After the array is filled, a second FOR loop with the same bounds shows every element on the screen.		CThe loop goes up to 10 but the array only has indexes 1 to 5, so it goes out of range. The loop should be FOR Index ← 1 TO 5.
4A 2D grid is filled using a loop inside a loop, with one index for the row and one for the column.		DOUTPUT Marks does not show each element. A second FOR loop is needed with OUTPUT Marks[Index] to display every element.
5DECLARE Marks : ARRAY[1:5] OF INTEGER FOR Index ← 1 TO 10 INPUT Marks[Index] NEXT Index		EStep 1 of the program: create the array before using it, with its bounds and data type.
6FOR Index ← 1 TO 5 INPUT Marks[Index] NEXT Index OUTPUT Marks		FStep 2 of the program: a loop that fills every element of the array with a value typed in by the user.

Definitions

DECLARE, FOR INPUT, FOR OUTPUT

Fill in the Blanks

Complete each line of code by filling in the missing parts.

DECLARE Marks : _____[1:5] OF INTEGER

FOR Count ← 1 TO 5 _____ Marks[Count] NEXT Count

FOR Count ← 1 TO 5 OUTPUT Names[Count] NEXT _____

FOR Row ← 1 TO 3 FOR Col ← 1 TO 4 INPUT Grid[Row, ___]

DECLARE Names : ARRAY[1:3] OF ______ FOR Index ← 1 TO 3 OUTPUT Names[Index]

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A DECLARE Pay:ARRAY[1:3] OF REAL

B FOR i ← 1 TO 3

C INPUT Pay(i)

D NEXT i

Question 2

A FOR i ← 1 TO 3

B INPUT Fee[i]

C ENDFOR

D FOR i ← 1 TO 3

E OUTPUT Fee[i]

F NEXT i

Question 3

A DECLARE Pay:ARRAY[1:3] REAL

B FOR i ← 1 TO 3

C INPUT Pay[i]

D NEXT i

Question 4

A DECLARE Grd:ARRAY[1:4] OF CHAR

B FOR i ← 1 TO 5

C INPUT Grd[i]

D NEXT i

Question 5

A FOR i ← 1 TO 3

B INPUT Mark[j]

C NEXT i

D FOR i ← 1 TO 3

E OUTPUT Mark[i]

F NEXT i

Answer Key

Writing a complete array program: declare, fill and output

Section A: Quick Questions

B — DECLARE the array, FOR loop with INPUT, FOR loop with OUTPUT

B — DECLARE StudentNames : ARRAY[1:5] OF STRING

A — FOR Index ← 1 TO 5 INPUT Marks[Index] NEXT Index

A — FOR Index ← 1 TO 30

A — OUTPUT StudentNames[Index]

Section B: Match the Pairs

DECLARE Marks : ARRAY[1:5] OF INTEGER → Step 1 of the program: create the array before using it, with its bounds and data type.

FOR Index ← 1 TO 5 INPUT Marks[Index] NEXT Index → Step 2 of the program: a loop that fills every element of the array with a value typed in by the user.

After the array is filled, a second FOR loop with the same bounds shows every element on the screen. → FOR Index ← 1 TO 5 OUTPUT Names[Index], Marks[Index] NEXT Index

A 2D grid is filled using a loop inside a loop, with one index for the row and one for the column. → FOR Row ← 1 TO 3 FOR Col ← 1 TO 4 INPUT Grid[Row, Col] NEXT Col NEXT Row

DECLARE Marks : ARRAY[1:5] OF INTEGER FOR Index ← 1 TO 10 INPUT Marks[Index] NEXT Index → The loop goes up to 10 but the array only has indexes 1 to 5, so it goes out of range. The loop should be FOR Index ← 1 TO 5.

FOR Index ← 1 TO 5 INPUT Marks[Index] NEXT Index OUTPUT Marks → OUTPUT Marks does not show each element. A second FOR loop is needed with OUTPUT Marks[Index] to display every element.

Section C: Definitions

DECLARE, FOR INPUT, FOR OUTPUT — The pattern of a complete array program: declare the array, use a FOR loop to INPUT a value into each element, then use a second FOR loop to OUTPUT every element.

Section D: Fill in the Blanks

DECLARE Marks : ARRAY[1:5] OF INTEGER

FOR Count ← 1 TO 5
   INPUT Marks[Count]
NEXT Count

FOR Count ← 1 TO 5
   OUTPUT Names[Count]
NEXT Count

FOR Row ← 1 TO 3
   FOR Col ← 1 TO 4
      INPUT Grid[Row, Col]

DECLARE Names : ARRAY[1:3] OF STRING
FOR Index ← 1 TO 3
   OUTPUT Names[Index]

Section E: Spot the Error

C — Array elements are accessed with square brackets, not round ones. It should be INPUT Pay[i].

C — A FOR loop in IGCSE pseudocode is closed with NEXT and the loop variable, not ENDFOR. Line 3 should be NEXT i.

A — The declaration is missing the keyword OF before the data type. It should be DECLARE Pay:ARRAY[1:3] OF REAL.

B — The array's upper bound is 4, so the loop must stop at 4. Going to 5 would cause an index out of range error. It should be FOR i ← 1 TO 4.

B — The loop variable is i, but the index uses j, which has no value. The index must be the loop variable, so it should be INPUT Mark[i].