[#BloombergLP-ball-CategoryManager_RadixTree-forEachPrefix-03]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/ball.adoc[ball]::xref:BloombergLP/ball/CategoryManager_RadixTree.adoc[CategoryManager_RadixTree]::forEachPrefix
:relfileprefix: ../../../
:mrdocs:

Call `functor` for each key‐value pair whose key starts with `prefix`.

== Synopsis

Declared in `<ball_categorymanager_radixtree.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_FUNCTOR>
xref:BloombergLP/ball/CategoryManager_RadixTree/size_type.adoc[CategoryManager_RadixTree<t_VALUE>::size_type]
forEachPrefix(
    std::string_view const& prefix,
    t_FUNCTOR const& functor) const;
----

== Description

The `functor` should be a callable object that accepts two parameters: `const bsl::string_view&` for the key and `const t_VALUE&` for the value. Return the number of times the functor was called. The order of visitation is unspecified. See also the manipulator variation that allows the functor to modify the value.

== Return Value

number of times the functor was called

== Parameters

[cols="1,4"]
|===
| Name| Description
| *prefix*
| key prefix to match
| *functor*
| callable invoked for each matching key‐value pair
|===


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