CMSC 313 - C Coding Standards

General Comments

Every programming department has a some set of standards or conventions that programmers are expected to follow. The purpose of these standards is make programs readable and maintainable. After all, you may be the programmer who maintains your own code more than 6 months after having written the original. While no two programming departments standards/conventions may be the same, it is important that all members of the department follow the same standards.
Neatness counts ! ! !
At UMBC, the following standards have been created and are followed in CMSC 313.

Part of every project grade is based upon how well these standards are followed.

It is your responsiblity to understand these standards. If you have any questions, ask your instructor, any of the TAs or the Help Center.

Naming Conventions

Use of Whitespace

The prudent use of whitespace (blank lines as well as space) goes a long way to making your program readable.

Use of Braces

  • Always use braces to mark the beginning and end of a loop or "if" structure, even when not required.
  • See the indentation standard for appropriate placement of braces.
    Work within an 80-character screen
    Whether writing code or having your program produce output, it should always fit into an 80 character wide screen. You should never let a statement wrap down to the beginning of the next line, since it obscures the indentation.


    Comments are the programmers main source of documentation. Comments for files, functions and code are described below.

    File Header Comments

    EVERY source file (.c and .h files) should contain an opening comment describing the contents of the file and other pertinent information. This "file header comment" MUST include the following information.
    1. The file name
    2. Your name
    3. The date the file was created
    4. Your section number
    5. Your UMBC e-mail address
    6. A description of the contents of the file
    For example /***************************************** ** File: proj4.c ** Author: Bob Smith ** Date: 4/22/06 ** Section:304 ** E-mail: ** ** This file contains the main driver program for project 4. ** This program reads the file specified as the first command line ** argument, counts the number of words, spaces, and characters and ** displays the results in the format specified in the project description ** ** Other files required are ** 1. proj4.h -- prototypes for the functions defined in this file ** 2. chars.c -- functions that count each type of character & words ** 3. chars.h -- prototypes for the functions defined in chars.c ** ***********************************************/

    Function Header Comments

    EACH FUNCTION must have a header comment that includes the following:
    1. function name
    2. a description of what the function does
    3. a description of the function's inputs
    4. a description of the function's outputs
    5. side effect of the function (if any -- this should be rare)
    For example: /************************************************ ** circleArea -- ** This function calculates the area of a circle ** with the specified radius ** Inputs: the circle's radius as a parameter ** Output: the circle's area as the return value **************************************************/ Function header comments are also required above the function prototypes, since the header file is designed to be used as an interface.

    In-Line Comments

    "In-line" comments are used to clarify what your code does, NOT how it does it. Well structured code will be broken into logical sections that perform a simple task. Each of these sections of code (typically starting with an 'if' statement, or a loop or a 'switch' should be documented. A particularly important line of code should also be commented. Do not comment every line of code. Trivial comments (/* increment x */) are worse than no comments at all.

    An in-line comment appears above the code to which it applies and is indented to the same level as the code. For example:

    /* check every element of the array */ for (i = 0; i < ARRAYSIZE; i++) { /* if it's odd, add one ** if even, do nothing */ if (array[i] % 2 == 1) { array[i]++; } } Endline comments are not allowed : for (i = 0; i < ARRAYSIZE; i++) /* check every element of the array */