Is there documentation that describes what C function names "stand for" (not what they do--rather, what the abreviated name means)?

Question

Sometimes I have a hard time deciphering what C function names stand for. For example: the function sigprocmask changes the set of blocked signals, but I have no clue what the abbreviation procmask means. The linux man page describes the behavior of the function, but does not mention the abbreviation.

Another example is the constant SIGWINCH. I understand it is a singal that a window sized has changed, but it would be handy to have that plainly stated "SIGWINCH = Signal Window Changed." Does anyone know of such a resource? I have looked at several, and they all described the behavior, but ignored abbrevations. Thanks!

Answer 1

I remember in my early days of learning C that knowing what the function abbreviation stand for helped me a lot. So this is an attempt to demystify the abbreviations.

This post focuses on the abbreviation, not on the meaning. Thus some important points need to be raised:

• some abbreviations do not make make sense just by themselves. Either because some words are implicit, or because the order of the letters is weird when expanding the abbreviation. For instance iswprint() is an abbreviation for "is wide printable". The meaning is "wide character is a printing character"

• some abbreviation are misleading. E.g. the FPE in SIGFPE stands for "Floating Point Exception", but the category is for arithmetic exceptions. E.g. qsort() stands for "quick sort" but the standard doesn't require this algorithm and it is usually implemented as a polymorphic sort.

---

Standard Library

Structure follows https://en.cppreference.com/w/c

Type Support

Symbol	Meaning
size_t	size type
ptrdiff_t	pointer difference type
NULL	null
max_align_t	maximum align type
offsetof	offset of
alignas	align as
alignof	align of
noreturn	no return

Program support utilities

Program termination

Symbol	Meaning
abort	abort
exit	exit
quick_exit	quick exit
_Exit	exit
atexit	at exit
at_quick_exit	at quick exit

Communicating with the environment

Symbol	Meaning
system	system
getenv	get environment (variables)
getenv_s	get environment (variables) safe

Signals

Symbol	Meaning
signal	signal
raise	raise
sig_atomic_t	signal atomic type
SIG_DFL	signal default
SIG_IGN	signal ignore
SIG_ERR	signal error

Signal Types

Symbol	Meaning
SIGTERM	signal termination
SIGSEGV	signal segmentation violation
SIGINT	signal interrupt
SIGILL	signal illegal instruction
SIGABRT	signal abnormal termination
SIGFPE	signal floating point exception

Non-local jumps

Symbol	Meaning
setjmp	set jump
longjmp	long jump

Types

Symbol	Meaning
jmp_buf	jump buffer

Variadic function

Symbol	Meaning
va_start	variable arguments start
va_end	variable arguments end
va_copy	variable arguments copy
va_arg	variable arguments' argument
va_list	variable arguments list

Memory management

Symbol	Meaning
malloc	memory allocation
calloc	clean allocation
aligned_alloc	aligned allocation
realloc	reallocate
free	free

Date and time utilities

TODO

String Library

Null-terminated byte strings

Character classification

Symbol	Meaning
isalnum	is alphanumeric
isalpha	is alphabetic
islower	is lowercase
isupper	is uppercase
isdigit	is digit
isxdigit	is hexadecimal digit
iscntrl	is control
isgraph	is graphic
isspace	is space
isblank	is blank
isprint	is printable
ispunct	is punctuation

Character manipulation

Symbol	Meaning
tolower	to lowercase
toupper	to uppercase

Conversions to numeric formats

Symbol	Meaning
atof	ASCII to floating-point
atoi	ASCII to int
atol	ASCII to long
atoll	ASCII to long long
strtol	string to long
strtoll	string to long long
strtoul	string to unsigned long
strtoull	string to unsigned long long
strtof	string to float
strtod	string to double
strtold	string to long double
strtoimax	string to intmax_t
strtoumax	string to uintmax_t

String manipulation

Symbol	Meaning
strcpy	string copy
strcpy_s	string copy safe
strncpy	string n copy
strncpy_s	string n copy safe
strcat	string concatenation
strcat_s	string concatenation safe
strncat	string n concatenation
strncat_s	string n concatenation safe
strxfrm	string transformation

String examination

Symbol	Meaning
strlen	string length
strlen_s	string length safe
strcmp	string comparison
strncmp	string n comparison
strcoll	string collation
strchr	string (find) character
strrchr	string reverse (find) character
strspn	string span
strcspn	string complementary span
strpbrk	string pointer break
strstr	string (find) string
strtok	string tokenization
strtok_s	string tokenization safe

Character array manipulation

Symbol	Meaning
memchr	memory (search) character
memcmp	memory comparison
memset	memory set
memset_s	memory set safe
memcpy	memory copy
memcpy_s	memory copy safe
memmove	memory move
memmove_s	memory move safe

Miscellaneous

Symbol	Meaning
strerror	string error
strerror_s	string error safe
strerrorlen_s	string error length safe

Null-terminated multibyte strings

Multibyte/wide character conversions

Symbol	Meaning
mblen	multibyte length
mbtowc	multibyte to wide character
wctomb	wide character to multibyte
wctomb_s	wide character to multibyte safe
mbstowcs	multibyte string to wide character string
mbstowcs_s	multibyte string to wide character string safe
wcstombs	wide character string to multibyte string
wcstombs_s	wide character string to multibyte string safe
mbsinit	mbstate_t initialization
btowc	byte to wide character
wctob	wide character to byte
mbrlen	multibyte reentrant length
mbrtowc	multibyte reentrant to wide character
wcrtomb	wide character reentrant to multibyte
wcrtomb_s	wide character reentrant to multibyte safe
mbsrtowcs	multibyte string reentrant to wide character string
mbsrtowcs_s	multibyte string reentrant to wide character string safe
wcsrtombs	wide character string reentrant to multibyte string
wcsrtombs_s	wide character string reentrant to multibyte string safe
mbrtoc16	multibyte reentrant to char16_t
c16rtomb	char16_t reentrant to multibyte
mbrtoc32	multibyte reentrant to char32_t
c32rtomb	char32_t reentrant to multibyte

Types

Symbol	Meaning
mbstate_t	multibyte state type
char16_t	character 16-bit type
char32_t	character 32-bit type

Null-terminated wide strings

Character classification

Symbol	Meaning
iswalnum	is wide alphanumeric
iswalpha	is wide alphabetic
iswlower	is wide lowercase
iswupper	is wide uppercase
iswdigit	is wide digit
iswxdigit	is wide hexadecimal
iswcntrl	is wide control
iswgraph	is wide graphic
iswspace	is wide space
iswblank	is wide blank
iswprint	is wide printable
iswpunct	is wide punctuation
iswctype	is wide character type
wctype	wide character type

Character manipulation

Symbol	Meaning
towlower	to wide lowercase
towupper	to wide uppercase
towctrans	to wide character transformation
wctrans	wide character transformation

Conversions to numeric formats

Symbol	Meaning
wcstol	wide character string to long
wcstoll	wide character string to long long
wcstoul	wide character string to unsigned long
wcstoull	wide character string to unsigned long long
wcstof	wide character string to float
wcstod	wide character string to double
wcstold	wide character string to long double
wcstoimax	wide character string to intmax_t
wcstoumax	wide character string to uintmax_t

String manipulation

Symbol	Meaning
wcscpy	wide character string copy
wcscpy_s	wide character string copy safe
wcsncpy	wide character string n copy
wcsncpy_s	wide character string n copy safe
wcscat	wide character string concatenation
wcscat_s	wide character string concatenation safe
wcsncat	wide character string n concatenation
wcsncat_s	wide character string n concatenation safe
wcsxfrm	wide character string transformation

String examination

Symbol	Meaning
wcslen	wide character string length
wcslen_s	wide character string length safe
wcscmp	wide character string comparison
wcsncmp	wide character string n comparison
wcscoll	wide character string collation
wcschr	wide character string (find) character
wcsrchr	wide character string reverse (find) character
wcsspn	wide character string span
wcscspn	wide character string complementary span
wcspbrk	wide character string pointer break
wcsstr	wide character string (find) string
wcstok	wide character string tokenization
wcstok_s	wide character string tokenization safe

Wide character array manipulation

Symbol	Meaning
wmemchr	wide memory (search) character
wmemcmp	wide memory comparison
wmemset	wide memory set
wmemcpy	wide memory copy
wmemcpy_s	wide memory copy safe
wmemmove	wide memory move
wmemmove_s	wide memory move safe

Types

Symbol	Meaning
wchar_t	wide character type
wint_t	wide integer type
wctrans_t	wide character transformation type
wctype_t	wide character type type

Algorithms

Symbol	Meaning
qsort	quick sort
qsort_s	quick sort safe
bsearch	binary search
bsearch_s	binary search safe

Numerics

Mathematical functions

TODO

Floating-point environment

TODO

Pseudo-random number generation

TODO

Complex number arithmetic

TODO

Type-generic math

TODO

Input/output support

TODO

Localization support

TODO

Atomic operations library

TODO

Thread support library

TODO

POSIX

TODO