Meaningful identifiers for arrays, procedures and functions

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which is the better identifier for an array that stores student names?

A StudentNames

B x

2. Which is the better name for a function that works out a total?

A Total_stuff

B CalculateTotal

3. Which is the better name for a procedure that shows a menu on screen?

A p1

B DisplayMenu

4. Which statement about naming arrays is correct?

A Use a noun that describes the data stored, e.g. StudentNames

B Use a verb that describes an action, e.g. FillNames

5. Which statement about naming procedures and functions is correct?

A Start with a verb to show the action, e.g. DisplayMenu

B Use a noun for the data, e.g. MenuList

Match the Pairs

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

Left column		Right column
1StudentNames		APROCEDURE DisplayMenu()
2CalculateTotal		BA good array identifier: a PascalCase noun that shows the array stores a list of student names
3A procedure that shows a menu on screen should have a verb-based PascalCase name		CThe function name is a lowercase noun. It should be a PascalCase verb phrase such as CalculateTotal.
4An array holding exam scores should be named with a noun in PascalCase		DThe array name x is meaningless. It should be a descriptive PascalCase noun such as StudentNames.
5DECLARE x : ARRAY[1:30] OF STRING		EDECLARE ExamScores : ARRAY[1:30] OF INTEGER
6FUNCTION total(Price : REAL) RETURNS REAL		FA good function identifier: a PascalCase verb phrase that shows the function works out a total

Definitions

PascalCase

Fill in the Blanks

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

DECLARE ____________ : ARRAY[1:30] OF STRING

PROCEDURE ___________() OUTPUT "1. Start" ENDPROCEDURE

Total ← ______________(Price, Qty)

CALL ___________() INPUT Choice

FUNCTION ______________() RETURNS REAL RETURN Price * Qty ENDFUNCTION

Spot the Error

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

Question 1

A StudentNames[1] ← "Ava"

B x[2] ← "Liam"

C OUTPUT StudentNames[1]

Question 2

A PROCEDURE displaymenu()

B OUTPUT "1. Play"

C OUTPUT "2. Quit"

D ENDPROCEDURE

Question 3

A Price ← 12.5

B // Work out the total cost

C Total ← Maths(Price)

D OUTPUT Total

Question 4

A GetScores[1] ← 78

B ExamScores[2] ← 91

C OUTPUT ExamScores[2]

Question 5

A PROCEDURE DisplayMenu()

B OUTPUT "1. Play"

C ENDPROCEDURE

D CALL Menu()

Answer Key

Meaningful identifiers for arrays, procedures and functions

Section A: Quick Questions

A — StudentNames

B — CalculateTotal

B — DisplayMenu

A — Use a noun that describes the data stored, e.g. StudentNames

A — Start with a verb to show the action, e.g. DisplayMenu

Section B: Match the Pairs

StudentNames → A good array identifier: a PascalCase noun that shows the array stores a list of student names

CalculateTotal → A good function identifier: a PascalCase verb phrase that shows the function works out a total

A procedure that shows a menu on screen should have a verb-based PascalCase name → PROCEDURE DisplayMenu()

An array holding exam scores should be named with a noun in PascalCase → DECLARE ExamScores : ARRAY[1:30] OF INTEGER

DECLARE x : ARRAY[1:30] OF STRING → The array name x is meaningless. It should be a descriptive PascalCase noun such as StudentNames.

FUNCTION total(Price : REAL) RETURNS REAL → The function name is a lowercase noun. It should be a PascalCase verb phrase such as CalculateTotal.

Section C: Definitions

PascalCase — Each word starts with a capital. Name arrays with nouns (StudentNames); name functions and procedures with verbs (CalculateTotal, DisplayMenu) to show what they store or do.

Section D: Fill in the Blanks

DECLARE StudentNames : ARRAY[1:30] OF STRING

PROCEDURE DisplayMenu()
   OUTPUT "1. Start"
ENDPROCEDURE

Total ← CalculateTotal(Price, Qty)

CALL DisplayMenu()
INPUT Choice

FUNCTION CalculateTotal() RETURNS REAL
   RETURN Price * Qty
ENDFUNCTION

Section E: Spot the Error

B — The array name x says nothing about what it stores. Arrays should have descriptive PascalCase noun names, so this line should use StudentNames[2].

A — The identifier is all lower case, so the words are hard to read. PascalCase starts each word with a capital: DisplayMenu.

C — Maths is a vague noun that does not say what the function does. Functions should have verb names such as CalculateTotal.

A — GetScores is a verb, which suggests an action. An array stores data, so it needs a noun name such as ExamScores.

D — Menu is a noun and does not match the procedure that was declared. The procedure is named with a verb, DisplayMenu, so the call should be CALL DisplayMenu().