[#BloombergLP-bdlt-Datetime-operator_plus_eq-02] = xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlt.adoc[bdlt]::xref:BloombergLP/bdlt/Datetime.adoc[Datetime]::operator+= :relfileprefix: ../../../ :mrdocs: Add to this object the value of the specified `rhs` object, and return a reference providing modifiable access to this object. If `24 == hour()` on entry, set the `hour` attribute of this object to 0 before performing the addition. The behavior is undefined unless the resulting value is valid for `Datetime` (see `isValid`). == Synopsis Declared in `<bdlt_datetime.h>` [source,cpp,subs="verbatim,replacements,macros,-callouts"] ---- xref:BloombergLP/bdlt/Datetime.adoc[Datetime]& operator+=(xref:BloombergLP/bdlt/DatetimeInterval.adoc[DatetimeInterval] const& rhs); ---- [.small]#Created with https://www.mrdocs.com[MrDocs]#