[#BloombergLP-bdls-FdStreamBuf_FileHandler-seek]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdls.adoc[bdls]::xref:BloombergLP/bdls/FdStreamBuf_FileHandler.adoc[FdStreamBuf_FileHandler]::seek
:relfileprefix: ../../../
:mrdocs:

Set the file position associated with this object according to the specified `offset` and `dir` behavior.

== Synopsis

Declared in `<bdls_fdstreambuf.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
std::streampos
seek(
    std::streamoff offset,
    xref:BloombergLP/bdls/FilesystemUtil/Whence.adoc[FilesystemUtil::Whence] dir);
----

== Description

* If 'dir' is 'FilesystemUtil::e_SEEK_FROM_BEGINNING', set the position to 'offset' bytes from the beginning of the file. * If 'dir' is 'FilesystemUtil::e_SEEK_FROM_CURRENT', advance the position by 'offset' bytes * If 'dir' is 'FilesystemUtil::e_SEEK_FROM_END', set the position to 'offset' bytes beyond the end of the file.

Return the new location of the file position, in bytes from the beginning of the file on success; and `FilesystemUtil::k_INVALID_FD` otherwise. The effect on the file position is undefined unless the file descriptor represents a device capable of seeking. Note that `seek` does not change the size of the file if the position advances beyond the end of the file; instead, the next write at the pointer will increase the file size. Also note that on Windows in text mode, `offset` will be the number of bytes on disk passed over, including `r`s in `\r
` sequences.


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