1FPUTS(3P) POSIX Programmer's Manual FPUTS(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 fputs — put a string on a stream
13
15 #include <stdio.h>
16 int fputs(const char *restrict s, FILE *restrict stream);
18
20 The functionality described on this reference page is aligned with the
21 ISO C standard. Any conflict between the requirements described here
22 and the ISO C standard is unintentional. This volume of POSIX.1‐2017
23 defers to the ISO C standard.
24 The fputs() function shall write the null-terminated string pointed to
26 by s to the stream pointed to by stream. The terminating null byte
27 shall not be written.
28 The last data modification and last file status change timestamps of
30 the file shall be marked for update between the successful execution of
31 fputs() and the next successful completion of a call to fflush() or
32 fclose() on the same stream or a call to exit() or abort().
33
35 Upon successful completion, fputs() shall return a non-negative number.
36 Otherwise, it shall return EOF, set an error indicator for the stream,
37 and set errno to indicate the error.
38
40 Refer to fputc().
41 The following sections are informative.
43
45 Printing to Standard Output
46 The following example gets the current time, converts it to a string
47 using localtime() and asctime(), and prints it to standard output using
48 fputs(). It then prints the number of minutes to an event for which it
49 is waiting.
50 #include <time.h>
53 #include <stdio.h>
54 ...
55 time_t now;
56 int minutes_to_event;
57 ...
58 time(&now);
59 printf("The time is ");
60 fputs(asctime(localtime(&now)), stdout);
61 printf("There are still %d minutes to the event.\n",
62 minutes_to_event);
63 ...
64
66 The puts() function appends a <newline> while fputs() does not.
67 This volume of POSIX.1‐2017 requires that successful completion simply
69 return a non-negative integer. There are at least three known different
70 implementation conventions for this requirement:
71 * Return a constant value.
73 * Return the last character written.
75 * Return the number of bytes written. Note that this implementation
77 convention cannot be adhered to for strings longer than {INT_MAX}
78 bytes as the value would not be representable in the return type of
79 the function. For backwards-compatibility, implementations can
80 return the number of bytes for strings of up to {INT_MAX} bytes,
81 and return {INT_MAX} for all longer strings.
82
84 The fputs() function is one whose source code was specified in the ref‐
85 erenced The C Programming Language. In the original edition, the func‐
86 tion had no defined return value, yet many practical implementations
87 would, as a side-effect, return the value of the last character written
88 as that was the value remaining in the accumulator used as a return
89 value. In the second edition of the book, either the fixed value 0 or
90 EOF would be returned depending upon the return value of ferror(); how‐
91 ever, for compatibility with extant implementations, several implemen‐
92 tations would, upon success, return a positive value representing the
93 last byte written.
94
96 None.
97
99 Section 2.5, Standard I/O Streams, fopen(), putc(), puts()
100 The Base Definitions volume of POSIX.1‐2017, <stdio.h>
102
104 Portions of this text are reprinted and reproduced in electronic form
105 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
106 table Operating System Interface (POSIX), The Open Group Base Specifi‐
107 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
108 Electrical and Electronics Engineers, Inc and The Open Group. In the
109 event of any discrepancy between this version and the original IEEE and
110 The Open Group Standard, the original IEEE and The Open Group Standard
111 is the referee document. The original Standard can be obtained online
112 at http://www.opengroup.org/unix/online.html .
113 Any typographical or formatting errors that appear in this page are
115 most likely to have been introduced during the conversion of the source
116 files to man page format. To report such errors, see https://www.ker‐
117 nel.org/doc/man-pages/reporting_bugs.html .
118IEEE/The Open Group 2017 FPUTS(3P)