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

Set the file pointer associated with `descriptor` according to `whence`.

== Synopsis

Declared in `<bdls_filesystemutil.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
static
xref:BloombergLP/bdls/FilesystemUtil/Offset.adoc[Offset]
seek(
    xref:BloombergLP/bdls/FilesystemUtil/FileDescriptor.adoc[FileDescriptor] descriptor,
    xref:BloombergLP/bdls/FilesystemUtil/Offset.adoc[Offset] offset,
    int whence);
----

== Description

Set the file pointer associated with the specified `descriptor` (used by calls to the `read` and `write` system calls) according to the specified `whence` behavior: ` * If 'whence' is e_SEEK_FROM_BEGINNING, set the pointer to 'offset' bytes from the beginning of the file. * If 'whence' is e_SEEK_FROM_CURRENT, advance the pointer by 'offset' bytes * If 'whence' is e_SEEK_FROM_END, set the pointer to 'offset' bytes beyond the end of the file. ` Return the new location of the file pointer, in bytes from the beginning of the file, on success; and ‐1 otherwise. The effect on the file pointer is undefined unless the file is on a device capable of seeking. Note that `seek` does not change the size of the file if the pointer advances beyond the end of the file; instead, the next write at the pointer will increase the file size.

== Return Value

the new file‐pointer location on success, and ‐1 otherwise

== Parameters

[cols="1,4"]
|===
| Name| Description
| *descriptor*
| file descriptor whose file pointer is set
| *offset*
| byte offset applied according to `whence`
| *whence*
| starting point for the seek operation
|===


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