[#BloombergLP-bslx-TestInStream-seek] = xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslx.adoc[bslx]::xref:BloombergLP/bslx/TestInStream.adoc[TestInStream]::seek :relfileprefix: ../../../ :mrdocs: Set the index of the next byte to be extracted from this stream to the specified `offset` from the beginning of the stream, and validate this stream if it is currently invalid. The behavior is undefined unless `offset <= length()`. == Synopsis Declared in `<bslx_testinstream.h>` [source,cpp,subs="verbatim,replacements,macros,-callouts"] ---- void seek(std::size_t offset); ---- [.small]#Created with https://www.mrdocs.com[MrDocs]#