Principles of Software Engineering by Utpal Roy, Jadavpur University, Kolkata, India

1. CODING STANDARDS AND GUIDELINES
CODING STANDARDS
AND
GUIDELINES
Let’s Discuss
The
IDEAL Coding Attitude
January 13, 2012 Made By Utpal Ray 1

2. CODING STANDARDS AND GUIDELINES
CODING STANDARDS
Coding is a step to implement the design of the software system.
A program converts design intentions into an executable set of
instruction, and achieves the specified goal of the software.
The process is to write a program using suitable language.
Our goal is to write a program that is easy to understand, test,
modify and maintain.
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3. CODING STANDARDS AND GUIDELINES
PROGRAMMING STANDARDS AND PROCEDURES
If a program is given to three coders (programmers) to write, you will
get three different programs, achieving successfully the desired result.
So each must careful in their coding.
It is like traffic rules: they are to be followed for your own and others
safety, and also for the convenience of all who are on the road.
Coding standards are three types, namely
Universal, which is common irrespective of system.
Domain specific, which depends on particular platform like
Windows, Linix, Solaris, AIX, Embedded System etc.
Organization Specific. which depends upon where you are
developing code like, Oracle, SUN, HP, IBM, CISCO etc.
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4. CODING STANDARDS AND GUIDELINES
Programming style standards
Variable names should be mnemonic, clear and
simple e.g. “largest” rather than “x”.
Expressions should be clear and simple e.g.: abs
(x) <=0.01” rather than “(x<0.01) and (x> -0.01)”
Indentation and format
Indent bodies of structured statements at least 3 spaces
Leave blank lines between logically related groups of
statements, after the declarations, and between functions.
Wrap long lines at no more than 80 chars and indent the
continued statement further than the beginning of that statement.
Clearly delineate subprograms (procedures, functions, modules)
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5. CODING STANDARDS AND GUIDELINES
COMMENTING
Program should begin with a preface stating:
1. Programmers name
2. Date written
3. Course and assignment number
4. A summary or description of functionality i.e. what the program
does and a brief description of how to run it.
6. Any special instructions on how to run it.
5. Any known assumptions built into the program
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6. CODING STANDARDS AND GUIDELINES
Special Source Code Structure
static char rcsid[] = "$Id$";
/*
$Log$
*/
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7. CODING STANDARDS AND GUIDELINES
Program Robustness:
1. Do not check for equality among real numbers
2. Prevent the abnormal termination of a program due to input error,
check for the validity of the data when appropriate.
3. Programs should not be built around a specific data set, programs,
unless otherwise stated, should work correctly for any reasonable
test data set.
4. Do not use GOTO statements.
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8. CODING STANDARDS AND GUIDELINES
I/O Behavior: All I/O should use a proper format
1. All real number output should be formatted in decimal form unless
scientific notation is appropriate.
2. All input from the keyboard should be preceded by a prompt telling
the user what format is expected. For example “, Please input the date in
mm/dd/yy format”.
3. Label all output values
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9. CODING STANDARDS AND GUIDELINES
Modules and modular program structure
Module coherence: each module should correspond to one subtask in
the overall algorithm to solve the problem.
Module independence: each module should be independent .i.e it
should be self-contained and it should perform its task successfully
without needing to know the inner working of the calling module.
Procedures or functions should , in general occupy at most 50 lines.
Use appropriate parameters rather than global variables. Avoid side
effects.
Hide any information from the caller that it does not need. The default
should be to hide information unless the caller actually needs it.
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10. CODING STANDARDS AND GUIDELINES
Programming Guidelines
All programs have three main factors that need to be handled properly to
make a program efficient and effective for which it is written.
These three factors are:
1. Algorithms
How the problem gets solved in the program?
2. Control Structure
How the branching (if-then-else) and looping (while-true) should be
organized?
2. Data structures
How the data should be organized? (local vs. global, individual variable
vs. group of variables – data structure)
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11. CODING STANDARDS AND GUIDELINES
Indentation
Four spaces should be used as the unit of indentation. The exact
construction of the indentation (spaces vs. tabs) is unspecified. Tabs
must be set exactly every 8 spaces (not 4).
Line Length
Avoid lines longer than 80 characters, since they're not handled well
by many terminals and tools.
Wrapping Lines
When an expression will not fit on a single line, break it according to
these general principles:
Break after a comma.
Break before an operator.
Prefer higher-level breaks to lower-level breaks.
Align the new line with the beginning of the expression at the
same level on the previous line.
If the above rules lead to confusing code or to code that's squished up
against the right margin, just indent 8 spaces instead.
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12. CODING STANDARDS AND GUIDELINES
EXAMPLE of Bad INDENTATION
//DON'T USE THIS INDENTATION
if ((condition1 && condition2)
|| (condition3 && condition4)
||!(condition5 && condition6)) {
doSomethingAboutIt();
}
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13. CODING STANDARDS AND GUIDELINES
EXAMPLE of Good INDENTATION
if ((condition1 && condition2)
|| (condition3 && condition4)
||!(condition5 && condition6)) {
doSomethingAboutIt();
}
OR
if ((condition1 && condition2) || (condition3 && condition4)
||!(condition5 && condition6)) {
doSomethingAboutIt();
}
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14. CODING STANDARDS AND GUIDELINES
Three acceptable ways to format ternary expressions:
alpha = (aLongBooleanExpression) ? beta : gamma;
alpha = (aLongBooleanExpression) ? Beta
: gamma;
alpha = (aLongBooleanExpression)
? Beta
: gamma;
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15. CODING STANDARDS AND GUIDELINES
BLOCK COMMENT EXAMPLE
/*
* Here is a block comment.
*/
Block comments can start with /*-, which is recognized by indent(1) as
the beginning of a block comment that should not be reformatted.
Example:
* Here is a block comment with some very special
/*-
*
* formatting that I want indent(1) to ignore.
* one
* two
* three
*/
A block comment should be preceded by a blank line to set it
apart from the rest of the code.
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16. CODING STANDARDS AND GUIDELINES
Perfect Declarations Formatting
How many Declaration Per Line?
One declaration per line is recommended since it encourages
commenting.
In other words,
int level; // indentation level
int size; // size of table
is preferred over
int level, size;
Do not put different types on the same line. Example:
int foo, fooarray[]; //WRONG!
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17. CODING STANDARDS AND GUIDELINES
Single Line Statements
Each line should contain at most one statement. Example:
argv++; // Correct
argc--; // Correct
argv++; argc--; // AVOID!
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18. CODING STANDARDS AND GUIDELINES
The correct form of if, if-else, if else-if else Statements
if (condition) {
if (condition) { statements;
statements; } else {
} statements;
}
if (condition) {
statements;
} else if (condition) {
} else {
statements;
}
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19. CODING STANDARDS AND GUIDELINES
The correct form of for Statements
for (initialization; condition; update) {
When using the comma
statements;
operator in the
}
initialization or update
clause of a for
statement, avoid the
complexity of using
more than three
variables.
for (initialization; condition; update);
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20. CODING STANDARDS AND GUIDELINES
The correct form of do-while Statements
do {
statements;
} while (condition);
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21. CODING STANDARDS AND GUIDELINES
switch (condition) {
The correct form of
switch Statements case ABC:
statements;
/* falls through */
case DEF:
statements;
break;
case XYZ:
statements;
break;
default:
statements;
break;
}
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