1FSEEKO(3) Linux Programmer's Manual FSEEKO(3)
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6 fseeko, ftello - seek to or report file position
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9 #include <stdio.h>
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11 int fseeko(FILE *stream, off_t offset, int whence);
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13 off_t ftello(FILE *stream);
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15 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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17 fseeko(), ftello():
18 _FILE_OFFSET_BITS == 64 || _POSIX_C_SOURCE >= 200112L
19 (defining the obsolete _LARGEFILE_SOURCE macro also works)
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22 The fseeko() and ftello() functions are identical to fseek(3) and
23 ftell(3) (see fseek(3)), respectively, except that the offset argument
24 of fseeko() and the return value of ftello() is of type off_t instead
25 of long.
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27 On some architectures, both off_t and long are 32-bit types, but defin‐
28 ing _FILE_OFFSET_BITS with the value 64 (before including any header
29 files) will turn off_t into a 64-bit type.
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32 On successful completion, fseeko() returns 0, while ftello() returns
33 the current offset. Otherwise, -1 is returned and errno is set to
34 indicate the error.
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37 See the ERRORS in fseek(3).
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40 These functions are available under glibc since version 2.1.
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43 For an explanation of the terms used in this section, see
44 attributes(7).
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46 ┌───────────────────┬───────────────┬─────────┐
47 │Interface │ Attribute │ Value │
48 ├───────────────────┼───────────────┼─────────┤
49 │fseeko(), ftello() │ Thread safety │ MT-Safe │
50 └───────────────────┴───────────────┴─────────┘
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53 POSIX.1-2001, POSIX.1-2008, SUSv2.
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56 fseek(3)
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59 This page is part of release 5.02 of the Linux man-pages project. A
60 description of the project, information about reporting bugs, and the
61 latest version of this page, can be found at
62 https://www.kernel.org/doc/man-pages/.
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66 2017-09-15 FSEEKO(3)