Common Abbreviations Used in C Programming

A reference of common abbreviations used when naming source code identifiers like variables, functions, and macros in the C programming language.

Introduction

Cryptic abbreviations should be avoided in identifiers to ensure source code remains readable. However, completely avoiding abbreviations often results in verbose code that obscures intent.

The following list contains common abbreviations suitable for C source code. These abbreviations may also be used in other programming languages, provided they do not conflict with established naming conventions.

In the provided examples, multiple words in an identifier are concatenated with underscores (_), as seen in the function name get_address. The underscore may be omitted if the identifier is short and consists of abbreviations (e. g., err_msg vs. errmsg) or a word combined with an abbreviation.

List of Abbreviations

arg, args

argument. Used to refer to arguments, such as the command line arguments passed to a C program’s int main(int argc, char *argv[]) function.

buf

buffer. Example: Variable used as a buffer, e. g., char buf[20].

c

count. Used in variable names as a suffix to indicate that a variable contains the number of certain items, such as in the argc (argument count) parameter of a C program’s main function.

cat

category. Example: Variable term_cat, function find_cat.

cmd, CMD

command. Example: Definition #define CMD_OPEN 1.

dst, dest

destination. Example: Variable used as a destination of an operation, e. g., char dst[40].

err, ERR

error. Used as a variable containing an error code, such as err or as prefix for definitions of error codes, such as ERR_INVALID_VALUE. In the C standard library the error stream is named stderr.

ex, ext

extended, extension. Used to mark a function with extended functionality, e. g., replace_ex.

i

index. Example: Variable iend.

i, j, k

index. Loop counter variables.

id

identifier. Unique identifier used to reference a certain record. Example: Variable user_id.

len

length. Example: Variable file_len, definition LEN_MAX.

max, MAX

maximum. Used in variable names, constants, or definitions, e. g., INT_MAX.

mem

memory. Example: Variable mem_size.

min, MIN

minimum. See max, MAX.

msg

message. Example: Variable err_msg.

num, NUM

number, number of items. Used for numbered items, such as the variable room_num, or in macro definitions, such as #define NUM_ROOMS 24.

opt, opts

option. Example: Variable compile_opts.

p, ptr

pointer. Used as a suffix for a variable or parameter name, such as memptr or memp, to indicate that the variable is intended for pointer arithmetic as opposed to a simple reference to an entity.

pos

position. Example: Variable start_pos.

prev

previous. Used in contexts such as prev and next to indicate the previous element.

retval

return value. Used as a variable name to store a function’s return value.

s

Plural. Appended to indicate a plural, e. g., args, opts.

src

source. Example: Variable used as the source of a copy operation, e. g., char *src = "Hello".

std

standard. Used in the C standard library, e. g., in header filenames such as stdlib.h or in stream names such as stdin.

v, val

value. Used to indicate a value, e. g., in (key, val) or (k, v) pairs, or as a suffix indicating that a variable contains values, such as the char *argv[] (argument values) parameter of a C program’s main function.

var

variable.