[#bsl-vectorBase-0aa9-back-0e] = xref:bsl.adoc[bsl]::xref:bsl/vectorBase-0aa9.adoc[vectorBase<unsigned long long>]::back :relfileprefix: ../../ :mrdocs: Return a reference providing modifiable access to the last element in this vector. The behavior is undefined unless this vector is not empty. == Synopsis Declared in `<bslstl_vector.h>` [source,cpp,subs="verbatim,replacements,macros,-callouts"] ---- xref:bsl/vectorBase-0aa9/reference.adoc[reference] back(); ---- [.small]#Created with https://www.mrdocs.com[MrDocs]#