stdio(3s) [v7 man page]
STDIO(3S) STDIO(3S) NAME
stdio - standard buffered input/output package SYNOPSIS
#include <stdio.h> FILE *stdin; FILE *stdout; FILE *stderr; DESCRIPTION
The functions described in Sections 3S constitute an efficient 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> of pertinent macro definitions. The func- tions and constants mentioned in sections labeled 3S are declared in the include file and need no further declaration. 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. STDIO(3S)
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stdio(3S) stdio(3S) NAME
stdio() - standard buffered input/output stream file package SYNOPSIS
DESCRIPTION
The Standard I/O functions described in the subsection(3S) entries of this manual constitute an efficient, user-level I/O buffering scheme. The and functions handle characters quickly. The following functions all use or act as if they use and and can be freely inter- mixed: A file with associated buffering is called a stream and is declared to be a pointer to a defined type creates certain descriptive data for a stream and returns a pointer to designate the stream in all further transactions. Section(3S) library routines operate on this stream. At program startup, three streams, and are predefined and do not need to be explicitly opened. When opened, the standard input and stan- dard output streams are fully buffered if the output refers to a file and line-buffered if the output refers to a terminal. The standard error output stream is by default unbuffered. These three streams have the following constant pointers declared in the header file : standard input file standard output file standard error file A constant, NULL, (0) designates a nonexistent pointer. An integer-constant, (-1) is returned upon end-of-file or error by most integer functions that deal with streams (see individual descrip- tions for details). An integer constant specifies the size of the buffers used by the particular implementation (see setbuf(3S)). Any program that uses this package must include the header file of pertinent macro definitions as follows: The functions and constants mentioned in subsection(3S) entries of this manual are declared in that header file and need no further decla- ration. A constant defines the default maximum number of open files allowed per process. To increase the open file limit beyond this default value, see getrlimit(2). WARNINGS
Use of interfaces with a shared read/write file descriptor on will provide undefined behavior. Applications which are doing operations on need to use seperate file pointers for input and output, even if using the same file descriptor for both types of operations. ERRORS
Invalid stream pointers usually cause grave disorder, possibly including program termination. Individual function descriptions describe the possible error conditions. SEE ALSO
close(2), lseek(2), open(2), pipe(2), read(2), getrlimit(2), write(2), ctermid(3S), cuserid(3S), fclose(3S), ferror(3S), fgetpos(3S), fileno(3S), fopen(3S), fread(3S), fseek(3S), fgetpos(3S), getc(3S), gets(3S), popen(3S), printf(3S), putc(3S), puts(3S), scanf(3S), set- buf(3S), system(3S), tmpfile(3S), tmpnam(3S), ungetc(3S). STANDARDS CONFORMANCE
stdio(3S)