Copyright (c) 1980 Regents of the University of California.
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@(#)intro.3 6.9 (Berkeley) 06/23/90

C 4 intro - introduction to C library functions 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.

/usr/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

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

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