CS439: C Style Guidelines

Programming is not a dry mechanical process, but a form of art. Well written code has an aesthetic appeal while poor form can make other programmers and instructors cringe. Programming assignments will be graded based on style and correctness. Good programming practices usually include many of the following principles:

General Programming Style

• A comment at the top of the program that includes
  • Program authors
  • Date or Dates
  • A brief description of what the program does
• Concise comments that summarize major sections of your code
• Meaningful variable and function names
• Function comments that include: (1) description of what function does; (2) description of input values (parameter values); (3) description of return value(s)
• Well organized code
• White space or comments to improve legibility
• Avoidance of large blocks of copy-pasted code (use functions!)

Specific Guidelines

• Indentation: Use 3 spaces per indentation level, or some consistent number of spaces. Two spaces is probably not enough, more than 6 is probably too many.
  
• Tabs or Spaces: Never, ever, mix tabs and spaces.
  
• Limit lines to 80 characters. This avoids line wrapping.
• Blank lines: Use blank lines before and after a function definition, and to separate segments of code. Blank lines should be used to increase readability of your code. Do not separate every two statements by a blank line. 
• Whitespace:
  
• Do not use extra whitespace inside brackets and braces:
• Do this: myFunction(a[2], {1, 2})
• Not this: myFunction(  a[  2 ],   {  1,   2})
• In a function call, do not separate the function name and its argument list by whitespace:
• Do this: myFunction(1)
• Not this: myFunction  (1)
• Use a blank space before and after the = sign in an assignment statement: i = i+1
• Do not include multiple statements on the same line. This reduces readability.
• Separate an in-line comment from the statement by at least 2 blank spaces:
• i = i+1   /* add 1 to i */
•  Don't do this: i = i+1/*add 1 to i*/

• Use a couple of comments before a function or module to briefly describe what the function (or module) does. Likewise, before a chunk of related statements, include comments that describe briefly what the chunk does.
  
• Don't use too many in-line comments. If you feel a need for them, you probably aren't using enough comments at the beginning of functions and complicated code segments.
  

• Begin all variables with a lower case letter, except those that are naming a class or a struct
• All #define-s should be uppercase---multiple words may be separated by underscores.
• Use meaningful names. Except for a loop index, it's rarely a good idea to have a variable i or a variable x. An identifier's name should give the reader a clue about what it represents.
  

Acknowledgment

These style guidelines were written by Alison Norman.

Last updated: Sun Jan 20 12:05:14 -0600 2013 [validate xhtml]