NAME
stdio - standard buffered input/output package

SYNOPSIS
#include <stdio.h>

FILE *stdin;
FILE *stdout;
FILE *stderr;

DESCRIPTION
The functions listed below constitute a user-level buffering
scheme. The in-line macros getc and putc(3) handle characters
quickly. The higher level routines gets, fgets, scanf, fscanf,
fread, puts, fputs, printf, fprintf, fwrite all use getc and putc;
they can be freely intermixed.

A file with associated buffering is called a stream, and is
declared to be a pointer to a defined type FILE. Fopen(3) creates
certain descriptive data for a stream and returns a pointer to
designate the stream in all further transactions. There are three
normally open streams with constant pointers declared in the
include file and associated with the standard open files:

stdin standard input file
stdout standard output file
stderr standard error file

A constant ‘pointer’ NULL (0) designates no stream at all.

An integer constant EOF (-1) is returned upon end of file or error
by integer functions that deal with streams.

Any routine that uses the standard input/output package must
include the header file <stdio.h>. The constants, and the
following ‘functions’ are implemented as macros; redeclaration of
these names is perilous: getc, getchar, putc, putchar, feof,
ferror, fileno.

SEE ALSO
open(2), close(2), read(2), write(2)

DIAGNOSTICS
The value EOF is returned uniformly to indicate that a FILE pointer
has not been initialized with fopen, input (output) has been
attempted on an output (input) stream, or a FILE pointer designates
corrupt or otherwise unintelligible FILE data.

For purposes of efficiency, this implementation of the standard
library has been changed to line buffer output to a terminal by
default and attempts to do this transparently by flushing the
output whenever a read(2) from the standard input is necessary.
This is almost always transparent, but may cause confusion or
malfunctioning of programs which use standard i/o routines but use
read(2) themselves to read from the standard input.

In cases where a large amount of computation is done after printing
part of a line on an output terminal, it is necessary to fflush(3)
the standard output before going off and computing so that the
output will appear.

BUGS
The standard buffered functions do not interact well with certain
other library and system functions, especially vfork and abort.

LIST OF FUNCTIONS
Name Appears on Page Description

clearerr ferror(3) stream status inquiries
fclose fclose(3) close or flush a stream
fdopen fopen(3) open a stream
feof ferror(3) stream status inquiries
ferror ferror(3) stream status inquiries
fflush fclose(3) close or flush a stream
fgetc getc(3) get character or word from stream
fgetline fgetline(3) get a line from a stream
fgetpos fseek(3) reposition a stream
fgets gets(3) get a string from a stream
fileno ferror(3) stream status inquiries
fopen fopen(3) open a stream
fprintf printf(3) formatted output conversion
fpurge fclose(3) close or flush a stream
fputc putc(3) put character or word on a stream
fputs puts(3) put a string on a stream
fread fread(3) buffered binary input/output
freopen fopen(3) open a stream
fscanf scanf(3) formatted input conversion
fseek fseek(3) reposition a stream
fsetpos fseek(3) reposition a stream
ftell fseek(3) reposition a stream
fwrite fread(3) buffered binary input/output
funopen fopen(3) open a stream
getc getc(3) get character or word from stream
getchar getc(3) get character or word from stream
gets gets(3) get a string from a stream
getw getc(3) get character or word from stream
mktemp mktemp(3) make temporary file name (unique)
perror strerror(3) system error messages
printf printf(3) formatted output conversion
putc putc(3) put character or word on a stream
putchar putc(3) put character or word on a stream
puts puts(3) put a string on a stream
putw putc(3) put character or word on a stream
remove remove(3) remove directory entry
rewind fseek(3) reposition a stream
scanf scanf(3) formatted input conversion
setbuf setbuf(3) assign buffering to a stream
setbuffer setbuf(3) assign buffering to a stream
setlinebuf setbuf(3) assign buffering to a stream
setvbuf setbuf(3) assign buffering to a stream
snprintf printf(3) formatted output conversion
sprintf printf(3) formatted output conversion
sscanf scanf(3) formatted input conversion
strerror strerror(3) system error messages
sys_errlist strerror(3) system error messages
sys_nerr strerror(3) system error messages
tempnam tmpnam(3) temporary file routines
tmpfile tmpnam(3) temporary file routines
tmpnam tmpnam(3) temporary file routines
ungetc ungetc(3) push character back into input stream
vfprintf printf(3) formatted output conversion
vfscanf scanf(3) formatted input conversion
vprintf printf(3) formatted output conversion
vscanf scanf(3) formatted input conversion
vsnprintf printf(3) formatted output conversion
vsprintf printf(3) formatted output conversion
vsscanf scanf(3) formatted input conversion