[#BloombergLP-bslalg-RbTreeUtil-lowerBound-0c]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslalg.adoc[bslalg]::xref:BloombergLP/bslalg/RbTreeUtil.adoc[RbTreeUtil]::lowerBound
:relfileprefix: ../../../
:mrdocs:

Return the first node not ordered before `value`, or the sentinel.

== Synopsis

Declared in `<bslalg_rbtreeutil.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class NODE_VALUE_COMPARATOR,
    class VALUE>
static
xref:BloombergLP/bslalg/RbTreeNode.adoc[RbTreeNode] const*
lowerBound(
    xref:BloombergLP/bslalg/RbTreeAnchor.adoc[RbTreeAnchor] const& tree,
    NODE_VALUE_COMPARATOR& comparator,
    VALUE const& value);
----

== Description

Return the address of the leftmost node holding the smallest value greater‐than or equal‐to `value` in the specified `tree` (organized according to the specified 'comparator) if found, and return `tree.sentinel()` if `value` is greater‐than the rightmost node in `tree`. `COMPARATOR` shall be a functor providing two methods that can be called as if they had the following signatures: ` bool operator()(const RbTreeNode&, const VALUE&) const; bool operator()(const VALUE&, const RbTreeNode&) const; ` The behavior is undefined unless `comparator` provides a strict weak ordering on objects of type `VALUE`, and `tree` is well‐formed (`isWellFormed`). Note that this function returns the _first_ position before which `value` could be inserted into `tree` while preserving its ordering.

== Return Value

address of the first node not ordered before `value`, or the sentinel

== Parameters

[cols="1,4"]
|===
| Name| Description
| *tree*
| tree to search
| *comparator*
| functor used to order nodes against `value`
| *value*
| value whose lower bound is returned
|===


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