Meaningful identifiers for arrays

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which array name is better for storing 30 students' names?

A A

B StudentNames

2. Which statement is correct?

A An array identifier should describe what its elements hold

B An array identifier should be as short as possible

3. Which declaration uses a valid identifier for the array?

A DECLARE Scores : ARRAY[1:10] OF INTEGER

B DECLARE INPUT : ARRAY[1:10] OF INTEGER

4. In pseudocode, are StudentNames and studentnames the same identifier?

A Yes, identifiers are case insensitive

B No, they are two different arrays

5. Which identifier must NOT be used for an array?

A ForecastTemps

B FOR

Match the Pairs

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

Left column		Right column
1DECLARE StudentNames : ARRAY[1:30] OF STRING		AINPUT is a keyword, so it cannot be an array identifier. Use a name such as Scores instead.
2DECLARE FOR : ARRAY[1:10] OF INTEGER		BA meaningful array identifier: the name tells you the elements are student names
3Identifiers are case insensitive, so StudentNames and STUDENTNAMES refer to the same array		CStudentNames[1] ← "Ava" OUTPUT STUDENTNAMES[1]
4A plural name suits an array that holds many values of the same kind, such as several temperatures		DNot allowed: FOR is a keyword so it can never be used as an array identifier
5DECLARE A : ARRAY[1:30] OF STRING		EThe name A says nothing about the contents. It should be a meaningful name such as StudentNames.
6DECLARE INPUT : ARRAY[1:5] OF INTEGER INPUT[1] ← 20		FDECLARE Temperatures : ARRAY[1:7] OF REAL

Definitions

meaningful identifier

Fill in the Blanks

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

DECLARE StudentNames : ARRAY[1:30] OF STRING ____________[1] ← "Ava"

DECLARE Marks : ARRAY[1:5] OF INTEGER _____[2] ← 75

FOR Index ← 1 TO 3 _____ TeamNames[Index] NEXT Index

DECLARE StudentAges : ARRAY[1:30] OF _______

DECLARE ExamMarks : _____[1:20] OF INTEGER

Spot the Error

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

Question 1

A Scores[1] ← 75

B A[2] ← 82

C OUTPUT Scores[2]

Question 2

A FOR Pos ← 1 TO 3

B INPUT Prices[Pos]

C NEXT Pos

D OUTPUT Price[3]

Question 3

A Colours[1] ← "red"

B OUTPUT[2] ← "blue"

C OUTPUT Colours[2]

Question 4

A FOR Day ← 1 TO 7

B INPUT Names[Day]

C NEXT Day

D OUTPUT Temperatures[1]

Question 5

A StudentNames[1] ← "Ava"

B StudentNames[2] ← "Ben"

C Student Names[3] ← "Cy"

Answer Key

Meaningful identifiers for arrays

Section A: Quick Questions

B — StudentNames

A — An array identifier should describe what its elements hold

A — DECLARE Scores : ARRAY[1:10] OF INTEGER

A — Yes, identifiers are case insensitive

B — FOR

Section B: Match the Pairs

DECLARE StudentNames : ARRAY[1:30] OF STRING → A meaningful array identifier: the name tells you the elements are student names

DECLARE FOR : ARRAY[1:10] OF INTEGER → Not allowed: FOR is a keyword so it can never be used as an array identifier

Identifiers are case insensitive, so StudentNames and STUDENTNAMES refer to the same array → StudentNames[1] ← "Ava" OUTPUT STUDENTNAMES[1]

A plural name suits an array that holds many values of the same kind, such as several temperatures → DECLARE Temperatures : ARRAY[1:7] OF REAL

DECLARE A : ARRAY[1:30] OF STRING → The name A says nothing about the contents. It should be a meaningful name such as StudentNames.

DECLARE INPUT : ARRAY[1:5] OF INTEGER INPUT[1] ← 20 → INPUT is a keyword, so it cannot be an array identifier. Use a name such as Scores instead.

Section C: Definitions

meaningful identifier — An array name that says what its elements hold, like StudentNames not A. It must never be a keyword such as INPUT or FOR, and upper or lower case makes no difference.

Section D: Fill in the Blanks

DECLARE StudentNames : ARRAY[1:30] OF STRING
StudentNames[1] ← "Ava"

DECLARE Marks : ARRAY[1:5] OF INTEGER
MARKS[2] ← 75

FOR Index ← 1 TO 3
  INPUT TeamNames[Index]
NEXT Index

DECLARE StudentAges : ARRAY[1:30] OF INTEGER

DECLARE ExamMarks : ARRAY[1:20] OF INTEGER

Section E: Spot the Error

B — A is a meaningless name and it is not the same array as Scores. Use the descriptive identifier Scores: Scores[2] ← 82.

D — The array is called Prices. Price is a different identifier, so it would refer to an array that does not exist. Use the same plural name: OUTPUT Prices[3].

B — OUTPUT is a keyword, so it can never be used as an identifier. The array name should be Colours: Colours[2] ← "blue".

B — The array holds temperatures, so calling it Names is misleading and does not match the rest of the program. Use INPUT Temperatures[Day].

C — An identifier cannot contain a space. Write the name as one word: StudentNames[3] ← "Cy".