INTRO(3)

NAME
intro - introduction to C library functions

DESCRIPTION
This section describes functions that may be found in various libraries. The library functions are those other than the functions which directly invoke UNIX system primitives, described in section 2. Most of these functions are accessible from the C library, libc, which is automatically loaded by the C compiler cc(1), and the Pascal compiler pc(1). The link editor ld(1) searches this library under the `-lc' option. The C library also includes all the functions described in section 2.

A subset of these functions are available from Fortran; they are described separately in intro(3F).

The functions described in this section are grouped into various sections:

(3) The straight ``3'' functions are the standard C library functions.

(3N)
    These functions constitute the internet network library.

(3S)
    These functions constitute the `standard I/O package', see stdio(3S) for more details. Declarations for these functions may be obtained from the include file <stdio.h>.

(3C)
    These routines are included for compatibility with other systems. In particular, a number of system call interfaces provided in previous releases of 4BSD have been included for source code compatibility. Use of these routines should, for the most part, be avoided. The manual page entry for each compatibility routine indicates the proper interface to use.

(3M)
    These functions constitute the math library, libm. When functions in the math library (see math(3M)) are passed values that are undefined or would generate answers that are out of range, they call the infnan routine. By default this routine returns the VAX reserved floating point value which causes the process to get a floating point exception (see sigvec(2)). Programs that wish to take other action should define their own version of infnan (see infnan(3M) for details). The math library is loaded as needed by the Pascal compiler pc(1). C programs that wish to use this library need to specify the ``-lm'' option.

(3X)
    These functions constitute minor libraries and other miscellaneous run-time facilities. Most are available only when programming in C. These functions include libraries that provide device independent plotting functions, terminal independent screen management routines for two dimensional non-bitmap display terminals, and functions for managing data bases with inverted indexes. These functions are located in separate libraries indicated in each manual entry.

FILES
/lib/libc.a		the C library
/usr/lib/libm.a		the math library
/usr/lib/libc_p.a		the C library compiled for profiling
/usr/lib/libm_p.a		the math library compiled for profiling

SEE ALSO
stdio(3S), math(3M), intro(2), cc(1), ld(1), nm(1)

LIST OF FUNCTIONS

Name	Appears on Page	Description

abort	abort.3	generate a fault
abs	abs.3	integer absolute value
acos	sin.3m	inverse trigonometric function
acosh	asinh.3m	inverse hyperbolic function
alarm	alarm.3c	schedule signal after specified time
alloca	malloc.3	memory allocator
arc	plot.3x	graphics interface
asctime	ctime.3	convert date and time to ASCII
asin	sin.3m	inverse trigonometric function
asinh	asinh.3m	inverse hyperbolic function
assert	assert.3x	program verification
atan	sin.3m	inverse trigonometric function
atanh	asinh.3m	inverse hyperbolic function
atan2	sin.3m	inverse trigonometric function
atof	atof.3	convert ASCII to numbers
atoi	atof.3	convert ASCII to numbers
atol	atof.3	convert ASCII to numbers
bcmp	bstring.3	bit and byte string operations
bcopy	bstring.3	bit and byte string operations
bzero	bstring.3	bit and byte string operations
cabs	hypot.3m	complex absolute value
calloc	malloc.3	memory allocator
cbrt	sqrt.3m	cube root
ceil	floor.3m	integer no less than
circle	plot.3x	graphics interface
clearerr	ferror.3s	stream status inquiries
closedir	directory.3	directory operations
closelog	syslog.3	control system log
closepl	plot.3x	graphics interface
cont	plot.3x	graphics interface
copysign	ieee.3m	copy sign bit
cos	sin.3m	trigonometric function
cosh	sinh.3m	hyperbolic function
crypt	crypt.3	DES encryption
ctime	ctime.3	convert date and time to ASCII
curses	curses.3x	screen functions with ``optimal'' cursor motion
dbminit	dbm.3x	data base subroutines
delete	dbm.3x	data base subroutines
drem	ieee.3m	remainder
ecvt	ecvt.3	output conversion
edata	end.3	last locations in program
encrypt	crypt.3	DES encryption
end	end.3	last locations in program
endfsent	getfsent.3x	get file system descriptor file entry
endgrent	getgrent.3	get group file entry
endhostent	gethostbyname.3n	get network host entry
endnetent	getnetent.3n	get network entry
endprotoent	getprotoent.3n	get protocol entry
endpwent	getpwent.3	get password file entry
endservent	getservent.3n	get service entry
environ	execl.3	execute a file
erase	plot.3x	graphics interface
erf	erf.3m	error function
erfc	erf.3m	complementary error function
etext	end.3	last locations in program
exec	execl.3	execute a file
exece	execl.3	execute a file
execl	execl.3	execute a file
execle	execl.3	execute a file
execlp	execl.3	execute a file
exect	execl.3	execute a file
execv	execl.3	execute a file
execvp	execl.3	execute a file
exit	exit.3	terminate a process after flushing any pending output
exp	exp.3m	exponential
expm1	exp.3m	exp(x)-1
fabs	floor.3m	absolute value
fclose	fclose.3s	close or flush a stream
fcvt	ecvt.3	output conversion
feof	ferror.3s	stream status inquiries
ferror	ferror.3s	stream status inquiries
fetch	dbm.3x	data base subroutines
fflush	fclose.3s	close or flush a stream
ffs	bstring.3	bit and byte string operations
fgetc	getc.3s	get character or word from stream
fgets	gets.3s	get a string from a stream
fileno	ferror.3s	stream status inquiries
firstkey	dbm.3x	data base subroutines
floor	floor.3m	integer no greater than
fopen	fopen.3s	open a stream
fprintf	printf.3s	formatted output conversion
fputc	putc.3s	put character or word on a stream
fputs	puts.3s	put a string on a stream
fread	fread.3s	buffered binary input/output
free	malloc.3	memory allocator
frexp	frexp.3	split into mantissa and exponent
fscanf	scanf.3s	formatted input conversion
fseek	fseek.3s	reposition a stream
ftell	fseek.3s	reposition a stream
ftime	time.3c	get date and time
fwrite	fread.3s	buffered binary input/output
gcvt	ecvt.3	output conversion
getc	getc.3s	get character or word from stream
getchar	getc.3s	get character or word from stream
getdiskbyname	getdisk.3x	get disk description by its name
getenv	getenv.3	value for environment name
getfsent	getfsent.3x	get file system descriptor file entry
getfsfile	getfsent.3x	get file system descriptor file entry
getfsspec	getfsent.3x	get file system descriptor file entry
getfstype	getfsent.3x	get file system descriptor file entry
getgrent	getgrent.3	get group file entry
getgrgid	getgrent.3	get group file entry
getgrnam	getgrent.3	get group file entry
gethostbyaddr	gethostbyname.3n	get network host entry
gethostbyname	gethostbyname.3n	get network host entry
gethostent	gethostbyname.3n	get network host entry
getlogin	getlogin.3	get login name
getnetbyaddr	getnetent.3n	get network entry
getnetbyname	getnetent.3n	get network entry
getnetent	getnetent.3n	get network entry
getpass	getpass.3	read a password
getprotobyname	getprotoent.3n	get protocol entry
getprotobynumber	getprotoent.3n	get protocol entry
getprotoent	getprotoent.3n	get protocol entry
getpw	getpw.3	get name from uid
getpwent	getpwent.3	get password file entry
getpwnam	getpwent.3	get password file entry
getpwuid	getpwent.3	get password file entry
gets	gets.3s	get a string from a stream
getservbyname	getservent.3n	get service entry
getservbyport	getservent.3n	get service entry
getservent	getservent.3n	get service entry
getw	getc.3s	get character or word from stream
getwd	getwd.3	get current working directory pathname
gmtime	ctime.3	convert date and time to ASCII
gtty	stty.3c	set and get terminal state (defunct)
htonl	byteorder.3n	convert values between host and network byte order
htons	byteorder.3n	convert values between host and network byte order
hypot	hypot.3m	Euclidean distance
index	string.3	string operations
inet_addr	inet.3n	Internet address manipulation routines
inet_lnaof	inet.3n	Internet address manipulation routines
inet_makeaddr	inet.3n	Internet address manipulation routines
inet_netof	inet.3n	Internet address manipulation routines
inet_network	inet.3n	Internet address manipulation routines
infnan	infnan.3m	signals exceptions
initgroups	initgroups.3x	initialize group access list
initstate	random.3	better random number generator
insque	insque.3	insert/remove element from a queue
isalnum	ctype.3	character classification macros
isalpha	ctype.3	character classification macros
isascii	ctype.3	character classification macros
isatty	ttyname.3	find name of a terminal
iscntrl	ctype.3	character classification macros
isdigit	ctype.3	character classification macros
islower	ctype.3	character classification macros
isprint	ctype.3	character classification macros
ispunct	ctype.3	character classification macros
isspace	ctype.3	character classification macros
isupper	ctype.3	character classification macros
j0	j0.3m	bessel function
j1	j0.3m	bessel function
jn	j0.3m	bessel function
label	plot.3x	graphics interface
ldexp	frexp.3	split into mantissa and exponent
lgamma	lgamma.3m	log gamma function; (formerly gamma.3m)
lib2648	lib2648.3x	subroutines for the HP 2648 graphics terminal
line	plot.3x	graphics interface
linemod	plot.3x	graphics interface
localtime	ctime.3	convert date and time to ASCII
log	exp.3m	natural logarithm
logb	ieee.3m	exponent extraction
log10	exp.3m	logarithm to base 10
log1p	exp.3m	log(1+x)
longjmp	setjmp.3	non-local goto
malloc	malloc.3	memory allocator
mktemp	mktemp.3	make a unique file name
modf	frexp.3	split into mantissa and exponent
moncontrol	monitor.3	prepare execution profile
monitor	monitor.3	prepare execution profile
monstartup	monitor.3	prepare execution profile
move	plot.3x	graphics interface
nextkey	dbm.3x	data base subroutines
nice	nice.3c	set program priority
nlist	nlist.3	get entries from name list
ntohl	byteorder.3n	convert values between host and network byte order
ntohs	byteorder.3n	convert values between host and network byte order
opendir	directory.3	directory operations
openlog	syslog.3	control system log
openpl	plot.3x	graphics interface
pause	pause.3c	stop until signal
pclose	popen.3	initiate I/O to/from a process
perror	perror.3	system error messages
point	plot.3x	graphics interface
popen	popen.3	initiate I/O to/from a process
pow	exp.3m	exponential x**y
printf	printf.3s	formatted output conversion
psignal	psignal.3	system signal messages
putc	putc.3s	put character or word on a stream
putchar	putc.3s	put character or word on a stream
puts	puts.3s	put a string on a stream
putw	putc.3s	put character or word on a stream
qsort	qsort.3	quicker sort
rand	rand.3c	random number generator
random	random.3	better random number generator
rcmd	rcmd.3x	routines for returning a stream to a remote command
re_comp	regex.3	regular expression handler
re_exec	regex.3	regular expression handler
readdir	directory.3	directory operations
realloc	malloc.3	memory allocator
remque	insque.3	insert/remove element from a queue
rewind	fseek.3s	reposition a stream
rewinddir	directory.3	directory operations
rexec	rexec.3x	return stream to a remote command
rindex	string.3	string operations
rint	floor.3m	round to nearest integer
rresvport	rcmd.3x	routines for returning a stream to a remote command
ruserok	rcmd.3x	routines for returning a stream to a remote command
scalb	ieee.3m	exponent adjustment
scandir	scandir.3	scan a directory
scanf	scanf.3s	formatted input conversion
seekdir	directory.3	directory operations
setbuf	setbuf.3s	assign buffering to a stream
setbuffer	setbuf.3s	assign buffering to a stream
setegid	setuid.3	set user and group ID
seteuid	setuid.3	set user and group ID
setfsent	getfsent.3x	get file system descriptor file entry
setgid	setuid.3	set user and group ID
setgrent	getgrent.3	get group file entry
sethostent	gethostbyname.3n	get network host entry
setjmp	setjmp.3	non-local goto
setkey	crypt.3	DES encryption
setlinebuf	setbuf.3s	assign buffering to a stream
setnetent	getnetent.3n	get network entry
setprotoent	getprotoent.3n	get protocol entry
setpwent	getpwent.3	get password file entry
setrgid	setuid.3	set user and group ID
setruid	setuid.3	set user and group ID
setservent	getservent.3n	get service entry
setstate	random.3	better random number generator
setuid	setuid.3	set user and group ID
signal	signal.3	simplified software signal facilities
sin	sin.3m	trigonometric function
sinh	sinh.3m	hyperbolic function
sleep	sleep.3	suspend execution for interval
space	plot.3x	graphics interface
sprintf	printf.3s	formatted output conversion
sqrt	sqrt.3m	square root
srand	rand.3c	random number generator
srandom	random.3	better random number generator
sscanf	scanf.3s	formatted input conversion
stdio	intro.3s	standard buffered input/output package
store	dbm.3x	data base subroutines
strcat	string.3	string operations
strcmp	string.3	string operations
strcpy	string.3	string operations
strlen	string.3	string operations
strncat	string.3	string operations
strncmp	string.3	string operations
strncpy	string.3	string operations
stty	stty.3c	set and get terminal state (defunct)
swab	swab.3	swap bytes
sys_errlist	perror.3	system error messages
sys_nerr	perror.3	system error messages
sys_siglist	psignal.3	system signal messages
syslog	syslog.3	control system log
system	system.3	issue a shell command
tan	sin.3m	trigonometric function
tanh	sinh.3m	hyperbolic function
telldir	directory.3	directory operations
tgetent	termcap.3x	terminal independent operation routines
tgetflag	termcap.3x	terminal independent operation routines
tgetnum	termcap.3x	terminal independent operation routines
tgetstr	termcap.3x	terminal independent operation routines
tgoto	termcap.3x	terminal independent operation routines
time	time.3c	get date and time
times	times.3c	get process times
timezone	ctime.3	convert date and time to ASCII
tputs	termcap.3x	terminal independent operation routines
ttyname	ttyname.3	find name of a terminal
ttyslot	ttyname.3	find name of a terminal
ungetc	ungetc.3s	push character back into input stream
utime	utime.3c	set file times
valloc	valloc.3	aligned memory allocator
varargs	varargs.3	variable argument list
vlimit	vlimit.3c	control maximum system resource consumption
vtimes	vtimes.3c	get information about resource utilization
y0	j0.3m	bessel function
y1	j0.3m	bessel function
yn	j0.3m	bessel function