Programming Style

1
Programming Style

• Naming Guidelines
• Indentation Spacing
• Comments

2
Agenda

• Administrivia
• Course Information
• Workon Woes
• Lab 1 Turnin
• Lecture
• Programming Style

3
Programming Style Overview

• What is Style?
• How it looks
• Format
• Readability
• Clarity
• Programming conventions (idioms)
• Naming conventions
• Commenting
• Guidelines for consistency

• Common Guidelines
• Indent to show structure
• Comment, comment, comment
• Capitalize constants
• Meaningful variable names
• Write for clarity
• Avoid clever tricks

4
Why Does Style Matter?

• Purpose To make code easy to read
• Benefits
• Consistency, consistency, consistency
• Easier to understand
• Easier to change
• Discipline can reduce errors
• Real World Commentary

5
Naming Guidelines

• Purpose of Variable/Function Name
• Label object
• Information about its purpose
• General Guidelines
• Informative
• Concise
• Memorable
• Pronounceable

6
Naming Code Example
X X XX XXX Aretha SalesTax(Aretha) X
X LateFee(X1, X) XXX X X
Interest(X1, X)
Balance Balance LastPayment MonthlyTotal
NewPurchases SalesTax(NewPurchases) Balance
Balance LateFee(CustomerID, Balance)
MonthlyTotal Balance Balance
Interest(CustomerID, Balance)
Examples from Code Complete
7
K P Guidelines

• Use descriptive names for globals, short names
  for locals
• Conventions p for pointers, Globals, CONSTANTS,
  Hungarian Naming Convention
• variableName vs. variable_name
• Be consistent
• Use active names for functions
• Be accurate

8
Choosing Good Names

• State in words what variable represents
• Optimum name length (10 16)
• Problem space, not solution space
• What not how
• Use opposites precisely
• First/Last vs. First/End

• Can find better name than temp for temporary
  variable
• Give booleans names that imply True or False
• Use standard abbreviations, but be sure to be
  consistent
• Avoid variables with
• Similar meaning names
• Different meanings, but similar names

9
Indentation Spacing

• Write for clarity
• Make a statements meaning as transparent as
  possible
• Write the clearest code
• Use spaces for grouping
• Format for readability
• Be consistent

10
K P Guidelines

• Indent to show structure
• Use consistent indentation brace style
• Use the natural form for expressions
• Make use of language idioms
• Parenthesize to remove ambiguity
• Break up complex expressions
• Be clear
• Avoid side effects

11
Layout Fundamentals

• Good visual layout shows the logical structure
  of a program
• Objectives of Good Layout
• Consistently represent the logical structure
• Improve readability
• Withstand modifications

for (i 0 i lt MAX_ELEMTS i) LeftElmt Left
i Lefti Righti Righti LeftElmt
Examples from Code Complete
12
Layout Techniques

• White Space
• Grouping
• Blank Lines
• Alignment
• Indentation
• Parentheses
• Use more than you think you need

variable 12 4 3 7 / 8
Examples from Code Complete
13
Comments

• Purpose To increase understanding
• Point out important details
• Provide context/overview
• Misuse
• Do not state what the code clearly says
• Do not contradict the code
• Do not distract with elaborate formatting

14
K P Guidelines

• Dont belabor the obvious
• zerocount / Increment zero entry counter
  /
• Add something not immediately evident
• Collect information in once place
• Comment functions and global data
• Dont comment bad code, rewrite it
• If comment is longer than code
• Dont contradict the code
• Clarify, dont confuse
• Clearer code leads to fewer comments