stdio(3s)
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stdio Subroutine
standard buffered input/output package
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SYNTAX
#include <stdio.h>
FILE *stdin, *stdout, *stderr;
DESCRIPTION
The 3S entries in this manual constitute an efficient, user-level
I/O buffering scheme. The in-line macros getc(3S) and putc(3S)
handle characters quickly. The macros getchar and putchar, and
the higher-level routines fgetc, fgets, fprintf, fputc, fputs,
fread, fscanf, fwrite, gets, getw, printf, puts, putw, and scanf
all use or act as if they 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(3S)
creates certain descriptive data for a stream and returns a
pointer to designate the stream in all further transactions.
Normally, there are three open streams with constant pointers
declared in the <stdio.h> header file and associated with the
standard open files:
stdin standard input file
stdout standard output file
stderr standard error file
A constant NULL (0) designates a nonexistent pointer.
An integer-constant EOF (-1) is returned upon end-of-file or
error by most integer functions that deal with streams (see the
individual descriptions for details).
An integer constant BUFSIZ specifies the size of the buffers used
by the particular implementation.
Any program that uses this package must include the header file
of pertinent macro definitions, as follows:
#include <stdio.h>
The functions and constants for all 3S entries in this manual are
declared in the header file and need no further declaration. The
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stdio(3s)
constants and the following "functions" are implemented as
macros. Don't redeclare these names: getc, getchar, putc,
putchar, ferror, feof, clearerr, and fileno.
SEE ALSO
open(2), close(2), lseek(2), pipe(2), read(2), write(2),
ctermid(3S), cuserid(3S), fclose(3S), ferror(3S), fopen(3S),
fread(3S), fseek(3S), getc(3S), gets(3S), popen(3S), printf(3S),
putc(3S), puts(3S), scanf(3S), setbuf(3S), system(3S),
tmpfile(3S), tmpnam(3S), ungetc(3S).
DIAGNOSTICS
Invalid stream pointers will usually cause problems, possibly
including program termination. The description for each function
lists its possible error conditions.
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