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cb0f97b2 | 1 | .\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org> |
88796fd7 AC |
2 | .\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com> |
3 | .\" | |
4 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft | |
5 | .\" | |
6 | .\" | |
4c1c5274 | 7 | .TH size_t 3type (date) "Linux man-pages (unreleased)" |
88796fd7 | 8 | .SH NAME |
1971f613 | 9 | size_t, ssize_t \- count of bytes |
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10 | .SH LIBRARY |
11 | Standard C library | |
12 | .RI ( libc ) | |
13 | .SH SYNOPSIS | |
14 | .nf | |
15 | .B #include <stddef.h> | |
16 | .PP | |
17 | .BR typedef " /* ... */ " size_t; | |
1971f613 AC |
18 | .PP |
19 | .B #include <sys/types.h> | |
20 | .PP | |
21 | .BR typedef " /* ... */ " ssize_t; | |
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22 | .fi |
23 | .SH DESCRIPTION | |
1971f613 AC |
24 | .TP |
25 | .I size_t | |
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26 | Used for a count of bytes. |
27 | It is the result of the | |
28 | .IR sizeof () | |
29 | operator. | |
2325c425 | 30 | It is an unsigned integer type |
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31 | capable of storing values in the range |
32 | .RB [ 0 , | |
33 | .BR SIZE_MAX ]. | |
1971f613 AC |
34 | .TP |
35 | .I ssize_t | |
f9f25914 | 36 | Used for a count of bytes or an error indication. |
2325c425 | 37 | It is a signed integer type |
1971f613 AC |
38 | capable of storing values al least in the range |
39 | .RB [ \-1 , | |
40 | .BR SSIZE_MAX ]. | |
1971f613 AC |
41 | .SS Use with printf(3) and scanf(3) |
42 | .TP | |
43 | .I size_t | |
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44 | The length modifier for |
45 | .I size_t | |
46 | for the | |
47 | .BR printf (3) | |
48 | and the | |
49 | .BR scanf (3) | |
50 | families of functions is | |
51 | .BR z , | |
52 | resulting commonly in | |
53 | .B %zu | |
54 | or | |
55 | .B %zx | |
56 | for printing | |
57 | .I size_t | |
58 | values. | |
1971f613 AC |
59 | .TP |
60 | .I ssize_t | |
61 | Glibc and most other implementations provide a length modifier for | |
62 | .I ssize_t | |
63 | for the | |
64 | .BR printf (3) | |
65 | and the | |
66 | .BR scanf (3) | |
67 | families of functions, | |
68 | which is | |
69 | .BR z ; | |
70 | resulting commonly in | |
71 | .B %zd | |
72 | or | |
73 | .B %zi | |
74 | for printing | |
75 | .I ssize_t | |
76 | values. | |
77 | Although | |
78 | .B z | |
79 | works for | |
80 | .I ssize_t | |
81 | on most implementations, | |
82 | portable POSIX programs should avoid using it\(emfor example, | |
83 | by converting the value to | |
84 | .I intmax_t | |
85 | and using its length modifier | |
86 | .RB ( j ). | |
88796fd7 | 87 | .SH VERSIONS |
1971f613 AC |
88 | .TP |
89 | .I size_t | |
88796fd7 AC |
90 | .IR <aio.h> , |
91 | .IR <glob.h> , | |
92 | .IR <grp.h> , | |
93 | .IR <iconv.h> , | |
94 | .IR <mqueue.h> , | |
95 | .IR <pwd.h> , | |
96 | .IR <signal.h> , | |
97 | and | |
98 | .I <sys/socket.h> | |
99 | define | |
100 | .I size_t | |
101 | since POSIX.1-2008. | |
1971f613 AC |
102 | .TP |
103 | .I ssize_t | |
104 | .IR <aio.h> , | |
105 | .IR <mqueue.h> , | |
106 | and | |
107 | .I <sys/socket.h> | |
108 | define | |
109 | .I ssize_t | |
110 | since POSIX.1-2008. | |
3113c7f3 | 111 | .SH STANDARDS |
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112 | .PD 0 |
113 | .IR size_t : | |
801a509d | 114 | C99 and later; |
88796fd7 | 115 | POSIX.1-2001 and later. |
1971f613 AC |
116 | .PP |
117 | .IR ssize_t : | |
118 | POSIX.1-2001 and later. | |
119 | .PD | |
88796fd7 | 120 | .SH NOTES |
1971f613 AC |
121 | .TP |
122 | .I size_t | |
123 | The following headers also provide | |
124 | .IR size_t : | |
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125 | .IR <aio.h> , |
126 | .IR <glob.h> , | |
127 | .IR <grp.h> , | |
128 | .IR <iconv.h> , | |
129 | .IR <monetary.h> , | |
130 | .IR <mqueue.h> , | |
131 | .IR <ndbm.h> , | |
132 | .IR <pwd.h> , | |
133 | .IR <regex.h> , | |
134 | .IR <search.h> , | |
135 | .IR <signal.h> , | |
136 | .IR <stdio.h> , | |
137 | .IR <stdlib.h> , | |
138 | .IR <string.h> , | |
139 | .IR <strings.h> , | |
140 | .IR <sys/mman.h> , | |
141 | .IR <sys/msg.h> , | |
142 | .IR <sys/sem.h> , | |
143 | .IR <sys/shm.h> , | |
144 | .IR <sys/socket.h> , | |
145 | .IR <sys/types.h> , | |
146 | .IR <sys/uio.h> , | |
147 | .IR <time.h> , | |
148 | .IR <unistd.h> , | |
149 | .IR <wchar.h> , | |
150 | and | |
151 | .IR <wordexp.h> . | |
1971f613 AC |
152 | .TP |
153 | .I ssize_t | |
154 | The following headers also provide | |
155 | .IR ssize_t : | |
156 | .IR <aio.h> , | |
157 | .IR <monetary.h> , | |
158 | .IR <mqueue.h> , | |
159 | .IR <stdio.h> , | |
160 | .IR <sys/msg.h> , | |
161 | .IR <sys/socket.h> , | |
162 | .IR <sys/uio.h> , | |
163 | and | |
164 | .IR <unistd.h> . | |
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165 | .SH SEE ALSO |
166 | .BR read (2), | |
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167 | .BR readlink (2), |
168 | .BR readv (2), | |
169 | .BR recv (2), | |
170 | .BR send (2), | |
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171 | .BR write (2), |
172 | .BR fread (3), | |
173 | .BR fwrite (3), | |
174 | .BR memcmp (3), | |
175 | .BR memcpy (3), | |
176 | .BR memset (3), | |
177 | .BR offsetof (3), | |
1971f613 | 178 | .BR ptrdiff_t (3type) |