1STDIO(3S) STDIO(3S)
2
6 stdio - standard buffered input/output package
7
9 #include <stdio.h>
10 FILE *stdin;
12 FILE *stdout;
13 FILE *stderr;
14
16 The functions described in section 3S constitute a user-level buffering
17 scheme. The in-line macros getc and putc(3S) handle characters
18 quickly. The higher level routines gets, fgets, scanf, fscanf, fread,
19 puts, fputs, printf, fprintf, fwrite all use getc and putc; they can be
20 freely intermixed.
21 A file with associated buffering is called a stream, and is declared to
23 be a pointer to a defined type FILE. Fopen(3S) creates certain
24 descriptive data for a stream and returns a pointer to designate the
25 stream in all further transactions. There are three normally open
26 streams with constant pointers declared in the include file and associ‐
27 ated with the standard open files:
28 stdin standard input file
30 stdout standard output file
31 stderr standard error file
32 A constant `pointer' NULL (0) designates no stream at all.
34 An integer constant EOF (-1) is returned upon end of file or error by
36 integer functions that deal with streams.
37 Any routine that uses the standard input/output package must include
39 the header file <stdio.h> of pertinent macro definitions. The func‐
40 tions and constants mentioned in sections labeled 3S are declared in
41 the include file and need no further declaration. The constants, and
42 the following `functions' are implemented as macros; redeclaration of
43 these names is perilous: getc, getchar, putc, putchar, feof, ferror,
44 fileno.
45
47 open(2), close(2), read(2), write(2), fread(3S), fseek(3S), f*(3S)
48
50 The value EOF is returned uniformly to indicate that a FILE pointer has
51 not been initialized with fopen, input (output) has been attempted on
52 an output (input) stream, or a FILE pointer designates corrupt or oth‐
53 erwise unintelligible FILE data.
54 For purposes of efficiency, this implementation of the standard library
56 has been changed to line buffer output to a terminal by default and
57 attempts to do this transparently by flushing the output whenever a
58 read(2) from the standard input is necessary. This is almost always
59 transparent, but may cause confusion or malfunctioning of programs
60 which use standard i/o routines but use read(2) themselves to read from
61 the standard input.
62 In cases where a large amount of computation is done after printing
64 part of a line on an output terminal, it is necessary to fflush(3S) the
65 standard output before going off and computing so that the output will
66 appear.
67
69 The standard buffered functions do not interact well with certain other
70 library and system functions, especially vfork and abort.
71
73 Name Appears on Page Description
74 clearerr ferror.3s stream status inquiries
75 fclose fclose.3s close or flush a stream
76 fdopen fopen.3s open a stream
77 feof ferror.3s stream status inquiries
78 ferror ferror.3s stream status inquiries
79 fflush fclose.3s close or flush a stream
80 fgetc getc.3s get character or word from stream
81 fgets gets.3s get a string from a stream
82 fileno ferror.3s stream status inquiries
83 fopen fopen.3s open a stream
84 fprintf printf.3s formatted output conversion
85 fputc putc.3s put character or word on a stream
86 fputs puts.3s put a string on a stream
87 fread fread.3s buffered binary input/output
88 freopen fopen.3s open a stream
89 fscanf scanf.3s formatted input conversion
90 fseek fseek.3s reposition a stream
91 ftell fseek.3s reposition a stream
92 fwrite fread.3s buffered binary input/output
93 getc getc.3s get character or word from stream
94 getchar getc.3s get character or word from stream
95 gets gets.3s get a string from a stream
96 getw getc.3s get character or word from stream
97 printf printf.3s formatted output conversion
98 putc putc.3s put character or word on a stream
99 putchar putc.3s put character or word on a stream
100 puts puts.3s put a string on a stream
101 putw putc.3s put character or word on a stream
102 rewind fseek.3s reposition a stream
103 scanf scanf.3s formatted input conversion
104 setbuf setbuf.3s assign buffering to a stream
105 setbuffer setbuf.3s assign buffering to a stream
106 setlinebuf setbuf.3s assign buffering to a stream
107 sprintf printf.3s formatted output conversion
108 sscanf scanf.3s formatted input conversion
109 ungetc ungetc.3s push character back into input stream
1104th Berkeley Distribution May 13, 1986 STDIO(3S)