intro(3)

NAME

intro − introduction to the standard C library subroutines

SYNTAX

#include <stdio.h>

DESCRIPTION

This section describes the various library subroutines and then lists those subroutines that are grouped together with the standard C library. All library subroutines are identified by the section number at the top of the page. The subroutines that are grouped together with the standard C library are those from sections 3, 3j, 3s, and 3v.

The library sections numbers and their corresponding meaning are:

(3) These functions, together with those of Section 2 and those marked (3s), constitute the /lib/libc.a library, which is automatically loaded by the cc C compiler and the Fortran f77 compiler. Declarations for some of these functions may be obtained from include files indicated on the appropriate pages. The ld link editor automatically searches this library when the −lc option is specified.

(3j) These functions constitute the job control subroutines, which are in /usr/lib/libjobs.a (jobs library). For further information, read intro(3j).

(3s) These functions constitute the “standard I/O package,” which are in the /lib/libc.a library. Declarations for these functions may be obtained from the <stdio.h> include file. For further information, see stdio(3s).

(3v) These functions constitute the SYSTEM V subroutines, which are in the /lib/libcV.a library. The link editor searches this library when the −lcV option is specified. For further information about the SYSTEM V programming environment, see cc(1).

(3f) These functions constitute the Fortran library subroutines. For further information, see intro(3f).

(3m) These functions constitute the Math library subroutines. For further information, see intro(3m).

(3n) These functions constitute the internet network subroutines. For further information, read intro(3n).

(3x) These functions, which have not been given a distinctive caption, constitute the miscellaneous libraries. For further information, read intro(3x).

Standard C Library		Manual
Subroutines	Description	Page
a64l	Convert long integer and base-64 ASCII string	a64l(3)
abort	Generate IOT fault	abort(3)
abs	Integer absolute value	abs(3)
asctime	Convert date and time	ctime(3)
asctime	Convert date and time (SYSTEM V)	ctime(3v)
atof	Convert ASCII to numbers	atof(3)
atoi	Convert ASCII to numbers	atof(3)
atol	Convert ASCII to numbers	atof(3)
bcmp	Compare strings of bytes	bstring(3)
bcopy	Copy strings of bytes	bstring(3)
bsearch	Binary search sorted table	bsearch(3)
bzero	Place zero bytes to string	bstring(3)
calloc	Main memory allocator	malloc(3)
clock	Report CPU time used	clock(3)
closedir	Directory operation	directory(3)
closelog	Control system log	syslog(3)
clrerr	Stream status inquiry	ferror(3s)
crypt	Password encryption	crypt(3)
ctermid	Generate terminal file name	ctermid(3s)
ctime	Convert date and time	ctime(3)
ctime	Convert date and time (SYSTEM V)	ctime(3v)
cuserid	Get user login name of the	cuserid(3s)
dial	Establish terminal line connection	dial(3)
drand48	Uniformly distributed pseudo-random numbers	drand48(3)
ecvt	Output conversion	ecvt(3)
edata	Last locations in program	end(3)
encrypt	Password encryption	crypt(3)
end	Last locations in program	end(3)
endfsent	Get file system descriptor	getfsent(3)
endgrent	Get group file entry	getgrent(3)
endpwent	Get password entry	getpwent(3)
endutent	Access utmp file entry	getut(3)
erand48	Uniformly distributed pseudo-random numbers	drand48(3)
etext	Last locations in program	end(3)
fclose	Close a stream	fclose(3s)
fcvt	Output conversion	ecvt(3)
fdopen	Open a stream	fopen(3s)
feof	Stream status inquiry	ferror(3s)
ferror	Stream status inquiry	ferror(3s)
fflush	Flush a stream	fclose(3s)
ffs	Find first bit in string	bstring(3)
fgetc	Get character from stream	getc(3s)
fgetgrent	Get group file entry	getgrent(3)
fgetpwent	Get password file entry	getpwent(3)
fgets	Get string from stream	gets(3s)
fileno	Stream status inquiry	ferror(3s)
fopen	Open a stream	fopen(3s)
fprintf	Formatted output conversion	printf(3s)
fputc	Write character to Fortran logical unit	putc(3s)
fputs	Put string on stream	puts(3s)
fread	Buffered binary input/output	fread(3s)
free	Main memory allocator	malloc(3)
freopen	Open a stream	fopen(3s)
frexp	Split into mantissa and exponent	frexp(3)
fscanf	Formatted input conversion	scanf(3s)
fseek	Reposition stream	fseek(3s)
ftell	Reposition stream	fseek(3s)
ftok	Standard interprocess communication package	stdipc(3)
ftw	Walk file tree	ftw(3)
fwrite	Buffered binary input/output	fread(3s)
gcvt	Output conversion	ecvt(3)
getc	Get character/word from stream	getc(3s)
getchar	Get character/word from stream	getc(3s)
getcwd	Get path/name of current working directory	getcwd(3)
getenv	Value for environment name	getenv(3)
getfsent	Get file system descriptor file entry	getfsent(3)
getfsfile	Get file system descriptor file entry	getfsent(3)
getfsspec	Get file system descriptor file entry	getfsent(3)
getgrent	Get group file entry	getgrent(3)
getgrgid	Get group file entry	getgrent(3)
getgrnam	Get group file entry	getgrent(3)
getlogin	Get login name	getlogin(3)
getopt	Get option letter from argument vector	getopt(3)
getpass	Read a password	getpass(3)
getpw	Get name from UID	getpw(3)
getpwent	Get password file entry	getpwent(3)
getpwnam	Get password file entry	getpwent(3)
getpwuid	Get password file entry	getpwent(3)
gets	Get string from stream	gets(3s)
getutent	Access utmp file entry	getut(3)
getutid	Access utmp file entry	getut(3)
getutline	Access utmp file entry	getut(3)
getw	Get character/word from stream	getc(3s)
getwd	Get current working directory	getwd(3)
gmtime	Convert date and time	ctime(3)
gmtime	Convert date and time (SYSTEM V)	ctime(3v)
gsignal	Software signals	ssignal(3)
hcreate	Manage hash search tables	hsearch(3)
hdestroy	Manage hash search tables	hsearch(3)
hsearch	Manage hash search tables	hsearch(3)
index	String operation	string(3)
isalpha	Character classification	ctype(3)
isalnum	Character classification	ctype(3)
isascii	Character classification	ctype(3)
isatty	Find terminal port name	ttyname(3)
iscntrl	Character classification	ctype(3)
isdigit	Character classification	ctype(3)
isgraph	Character classification	ctype(3)
islower	Character classification	ctype(3)
isprint	Character classification	ctype(3)
ispunct	Character classification	ctype(3)
isspace	Character classification	ctype(3)
isupper	Character classification	ctype(3)
isxdigit	Character classification	ctype(3)
jrand48	Uniformly distributed pseudo-random numbers	drand48(3)
l3tol	Convert 3-byte and long integers	l3tol(3)
l64a	Convert long integer and base-64 ASCII string	a64l(3)
lcong48	Uniformly distributed pseudo-random numbers	drand48(3)
ldexp	Split into mantissa and exponent	frexp(3)
lfind	Linear search and update	lsearch(3)
localtime	Convert date and time	ctime(3)
localtime	Convert date and time (SYSTEM V)	ctime(3v)
lockf	Files record locking	lockf(3)
longjmp	Non-local goto	setjmp(3)
lrand48	Uniformly distributed pseudo-random numbers	drand48(3)
lsearch	Linear search and update	lsearch(3)
ltol3	Convert 3-byte and long integers	l3tol(3)
malloc	Main memory allocator	malloc(3)
memccpy	Memory operations	memory(3)
memchr	Memory operations	memory(3)
memcmp	Memory operations	memory(3)
memcpy	Memory operations	memory(3)
memset	Memory operations	memory(3)
mkdir	Make directory file	mkdir(3)
mktemp	Make unique file name	mktemp(3)
modf	Split into mantissa and exponent	frexp(3)
monitor	Prepare execution profile	monitor(3)
mrand48	Uniformly distributed pseudo-random numbers	drand48(3)
nlist	Get name list entry	nlist(3)
nrand48	Uniformly distributed pseudo-random numbers	drand48(3)
opendir	Directory operation	directory(3)
openlog	Control system log	syslog(3)
pclose	Initiate I/O to/from process	popen(3s)
perror	System error messages	perror(3)
popen	Initiate I/O to/from process	popen(3s)
printf	Formatted output conversion	printf(3s)
psignal	System signal messages	psignal(3)
putc	Put character or word on stream	putc(3s)
putchar	Put character or word on stream	putc(3s)
putenv	Change/add value to environment	putenv(3)
putpwent	Write password file entry	putpwent(3)
puts	Put string on stream	puts(3s)
pututline	Access utmp file entry	getut(3)
putw	Put character or word on stream	putc(3s)
qsort	Quick sort	qsort(3)
rand	Random number generator	rand(3)
re_comp	Regular expression handler	regex(3)
re_exec	Regular expression handler	regex(3)
readdir	Directory operation	directory(3)
realloc	Main memory allocator	malloc(3)
rename	Change file name	rename(3)
rewind	Reposition stream	fseek(3s)
rewinddir	Directory operation	directory(3)
rindex	String operation	string(3)
rmdir	Remove directory	rmdir(3)
scanf	Formatted input conversion	scanf(3s)
seed48	Uniformly distributed pseudo-random numbers	drand48(3)
seekdir	Directory operation	directory(3)
setbuf	Assign buffering to a stream	setbuf(3s)
setegid	Set effective group ID	seteuid(3)
seteuid	Set effective user ID	seteuid(3)
setkey	Set encryption key	crypt(3)
setrgid	Set real group ID	seteuid(3)
setruid	Set real user ID	seteuid(3)
setfsent	Get file system descriptor	getfsent(3)
setgrent	Get group file entry	getgrent(3)
setjmp	Non-local goto	setjmp(3)
setpwent	Get password file entry	getpwent(3)
setutent	Access utmp file entry	getut(3)
setvbuf	Assign buffering to stream	setbuf(3s)
sighold	Manage signals (job control)	sigset(3j)
sigignore	Manage signals (job control)	sigset(3j)
signal	Manage signals (job control)	sigset(3j)
sigpause	Manage signals (job control)	sigset(3j)
sigrelse	Manage signals (job control)	sigset(3j)
sigset	Manage signals (job control)	sigset(3j)
sleep	Suspend execution for interval	sleep(3)
sprintf	Formatted output conversion	printf(3s)
srand	Random number generator	rand(3)
srand48	Uniformly distributed pseudorandom numbers	drand48(3)
sscanf	Formatted input conversion	scanf(3s)
ssignal	Software signals	ssignal(3)
stdio	Standard buffered I/O package	stdio(3s)
strcat	String operation	string(3)
strchr	String operation	string(3)
strcmp	String comparison intrinsic functions	string(3)
strcpy	String operation	string(3)
strcspn	String operation	string(3)
strlen	String operation	string(3)
strncat	String operation	string(3)
strncmp	String operation	string(3)
strncpy	String operation	string(3)
strpbrk	String operation	string(3)
strrchr	String operation	string(3)
strspn	String operation	string(3)
strtod	Convert string to double-precision number	strtod(3)
strtok	String operation	string(3)
strtol	Convert string to integer	strtol(3)
swab	Swap bytes	swab(3)
syslog	Control system log	syslog(3)
system	Issue shell command	system(3s)
_toupper	Translate character	conv(3)
_tolower	Translate character	conv(3)
tdelete	Manage binary search trees	tsearch(3)
telldir	Directory operation	directory(3)
tfind	Manage binary search trees	tsearch(3)
tgetent	Terminal independent operation	termlib(3)
tempnam	Create temporary file name	tmpnam(3s)
tgetflag	Terminal independent operation	termlib(3)
tgetnum	Terminal independent operation	termlib(3)
tgetstr	Terminal independent operation	termlib(3)
tgoto	Terminal independent operation	termlib(3)
timezone	Convert date and time to ASCII	ctime(3)
tmpfile	Create temporary file	tmpfile(3s)
tmpnam	Create name for temporary file	tmpnam(3s)
toascii	Translate characters	conv(3)
tolower	Translate characters	conv(3)
toupper	Translate characters	conv(3)
tputs	Terminal independent operation routines	termlib(3)
tsearch	Manage binary search trees	tsearch(3)
ttyname	Find terminal name	ttyname(3)
ttyslot	Find terminal name	ttyslot(3)
ttyslot	Find terminal name (SYSTEM V)	ttyslot(3v)
twalk	Manage binary search trees	tsearch(3)
tzset	Convert date and time to ASCII	ctime(3v)
undial	Release semaphore	dial(3)
ungetc	Push character back into input stream	ungetc(3s)
utmpname	Access utmp file entry	getut(3)
vfprintf	Print formatted output of varargs list	vprintf(3s)
vprintf	Print formatted output of varargs list	vprintf(3s)
vsprintf	Print formatted output of varargs list	vprintf(3s)

DEFINITIONS

A character is any bit pattern able to fit into a byte on the machine. The null character is a character with value 0, represented in the C language as ’\0’. A character array is a sequence of characters. A null-terminated character array is a sequence of characters, the last of which is the null character. A string is a designation for a null-terminated character array. The null string is a character array containing only the null character. A NULL pointer is the value that is obtained by casting 0 into a pointer. The C language guarantees that this value will not match that of any legitimate pointer, so many functions that return pointers return it to indicate an error. NULL is defined as 0 in <stdio.h>; the user can include an appropriate definition if not using <stdio.h>.

Many groups of FORTRAN intrinsic functions have generic function names that do not require explicit or implicit type declaration. The type of the function will be determined by the type of its argument(s). For example, the generic function max will return an integer value if given integer arguments (max0), a real value if given real arguments (amax1), or a double-precision value if given double-precision arguments (dmax1).

WARNING

Many of the functions in the libraries call and/or refer to other functions and external variables described in this section and in section 2 (System Calls). If a program inadvertently defines a function or external variable with the same name, the presumed library version of the function or external variable may not be loaded. The lint(1) program checker reports name conflicts of this kind as “multiple declarations” of the names in question. Definitions for sections 2, 3, and 3s are checked automatically. Other definitions can be included by using the −l option (for example, −lm includes definitions for the Math Library, section 3m). Use of lint is highly recommended.

FILES

/lib/libc.a
/lib/libcV.aSYSTEM V compatibility library

ASSEMBLER

In assembly language these functions may be accessed by simulating the C calling sequence. For example, ecvt(3) might be called this way:

setd
mov$sign,−(sp)
mov$decpt,−(sp)
movndigit,−(sp)
movfvalue,−(sp)
jsrpc,_ecvt
add$14.,sp

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