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, which is automatically loaded by the C compiler.
The C library also includes all the functions described in section 2.
The functions described in this section are grouped into various sections:
stdio(3S), math(3M), intro(2), cc(1), ld(1), nm(1)
Standard C library 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 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 malloc_debug malloc.3 memory allocator malloc_error malloc.3 memory allocator malloc_good_size malloc.3 memory allocator malloc_size 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 malloc.3 memory allocator varargs varargs.3 variable argument list vfree malloc.3 memory allocator 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