Standards for Programming Style

WORK IN PROGRESS ... DON'T READ

Indentation and Line Breaks

Either three or four spaces should be used as the unit of indentation. Choose one standard and stick to it throughout the code.

Do not use tabs to indent text. If you are using Microsoft Visual C++ turn off the tabs option (go to Tools -> Options -> Text Editor -> C/C+ -> Tabs+ and click the insert spaces radio button; you can set the number of spaces to three or four here too).

Avoid lines longer than 80 characters, since they are not handled well by many terminals and tools.

When an expression will not fit on a single line, break it according to the following general principles.

• Break after a comma.
• Break before an operator.
• Align the new line with the beginning of the expression at the same level on the previous line.

For example, consider the following statements.

longName1 = longName2 * (longName3 + longName4 - longName5)
            + 4 * longName6;  // Good break
longName1 = longName2 * (longName3 + longName4
                         - longName5) + 4 * longName6;  // bad break: avoid

Declarations

Number Per Line

One declaration per line is recommended since it encourages commenting:

int level; // indentation level
int size;  // size of table

is preferable to:

int level, size;

Do not put different types on the same line:

  int foo, fooarray[]; //WRONG!

Initialization

Initialize local variables where they are declared. The only reason not to initialize a variable where it’s declared is if the initial value depends on some computation occurring first.

Placement

Put declarations only at the beginning of blocks. A block is any code surrounded by curly braces { and }. Don’t wait to declare variables until their first use. Ideally, declare all variables at the beginning of the method or function block.

void myMethod() {
  int int1 = 0; // beginning of method block
  if (condition) {
     int int2 = 0; // beginning of "if" block
     ...
  } 

}

Class Declarations

The following formatting rules should be followed:

• No space between a method name and the parenthesis ( starting its parameter list.
• The open brace { appears at the end of the same line as the declaration statement.
• Theclosingbrace}startsalinebyitselfindentedtomatchitscorrespondingopeningstatement.

class Sample {
        ...
}

• Methods are separated by a blank line

Statements

Simple Statements

Each line should contain at most one statement. For example:

argv++;         // Correct
argc++;         // Correct
argv++; argc--; // AVOID!

Compound Statements

Compound statements are statements that contain lists of statements enclosed in braces { statements }. See the following sections for examples.

• The enclosed statements should be indented one more level than the compound statement.
• The opening brace should be at the end of the line that begins the compound statement; the closing brace should begin a line and be indented to the beginning of the compound statement.
• Braces are used around all statements, even single statements, when they are part of a control structure, such as a if-else or for statement. This makes it easier to add statements without accidentally introducing bugs due to forgetting to add braces.

if (condition) {
   a = b;
}
else {
   a = c; 
}

return Statements A return statement with a value should not use parentheses unless they make the return value more obvious in some way. For example:

  return;
  return myDisk.size();
  return TRUE;

if,if-else,if else-if else Statements The if-else class of statements should have the following form:

if (condition) {
   statements;
}

if (condition) {
   statements;
} else {
   statements;
}
 
if (condition) {
   statements;
} else if (condition) {
   statements;
} else {
  statements;
}

Always use braces { }, with if statements. Don’t use

if (condition) //AVOID!
   statement;

for Statements A for statement should have the following form:

for (initialization; condition; update) {
   statements;
}

while Statements

A while statement should have the following form:

while (condition) {  
   statements;
}

do-while Statements A do-while statement should have the following form:

do {
   statements;
} while (condition);

switch Statements A switch statement should have the following form:

switch (condition) {
case ABC:
   statements;
    /* falls through */
case DEF:
   statements;
   break;
case XYZ:
   statements;
   break;
default:
   statements;
  break; 
}

Every time a case falls through (i.e. when it doesn’t include a break statement), add a comment where the break statement would normally be. This is shown in the preceding code example with the /* falls through */ comment.

Every switch statement should include a default case. The break in the default case is redundant, but it prevents a fall-through error if later another case is added.

Naming Conventions

C vs. C++

Naming conventions make programs more understandable by making them easier to read. Since DREAM software uses both the C language and the C++ language, sometimes using the imperative programming and object-oriented programming paradigms separately, sometimes using them together, we will adopt two different naming conventions, one for C and the other for C++. The naming conventions for C++ are derived from the JavaDoc standards.

C++ Language Conventions

The following are the naming conventions for identifiers when using C++ and the object-oriented paradigm.

Identifier Type	Rules for Naming	Examples
Classes	Class names should be nouns, in mixed case with	class ImageDisplay
	the first letter of each internal word capitalized	class MotorController
Methods	Method names should be verbs, in mixed case with	int grabImage()
	the first letter in lowercase, with the first	int setVelocity()
	letter of each internal word capitalized
Variables	variable names should be in mixed case with the	int i;
	first letter in lowercase, with the first letter	float f;
	of each internal word capitalized	double pixelValue;
Constants	The names of variables declared as constants	const int WIDTH = 4;
	should be all uppercase with words separated by
	underscores _
Type Names	Typedef names should use the same naming policy as	typedef uint16 ComponentType
	that used for class names
Enum Names	Enum names should use the same naming policy as	enum PinState {
	that used for class names.	PIN_OFF,
	Enum labels should should be all uppercase with	PIN_ON /code>
	words separated by underscores <code>_	};

C Language Conventions

The following are the naming conventions for identifies when using C and the imperative programming paradigm. 

Identifier Type	Rules for Naming	Examples
Functions	Function names should be all lowercase with words	int display_image()
	separated by underscores _}	void set_motor_control()
Variables	variable names should be all lowercase with words	int i;
	separated by underscores _}	float f;
	of each internal word capitalized	double pixel_value;
Constants	Constants should be all uppercase with words	#define WIDTH 4
	separated by underscores _}
#define	#define and macro names should all uppercase	#define SUB(a,b) ((a) - (b))
and Macros	with words separated by underscores _

And Finally: Where To Put The Opening Brace {

There are two main conventions on where to put the opening brace of a block. In this document, we have adopted the JavaDoc convention and put the brace on the same line as the statement preceding the block. For example:

class Sample {
   ...
}

while (condition) {
   statements;
}

The second convention is to place the brace on the line below the statement preceding the block and it indent it to the same level. For example:

class Sample
{
   ... 
}

while (condition)
{
   statements;
}

If you really hate the JavaDoc format, use the second format, but be consistent and stick to it throughout your code.