[#BloombergLP-bdlat-ArrayUtil-accessElementByCategory]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlat.adoc[bdlat]::xref:BloombergLP/bdlat/ArrayUtil.adoc[ArrayUtil]::accessElementByCategory
:relfileprefix: ../../../
:mrdocs:

Invoke a categorized accessor on an element of the specified array.

== Synopsis

Declared in `<bdlat_arrayutil.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class TYPE,
    class ACCESSOR>
static
int
accessElementByCategory(
    TYPE const& array,
    ACCESSOR& accessor,
    int index);
----

== Description

Invoke the specified `accessor` on the non‐modifiable element at the specified `index` of the specified `array` and on a prvalue of the category tag type for the dynamic category of the element. See {`bdlat_typecategory`|Category Tags and Enumerators} for documentation about category tags. Return the value from the invocation of `accessor`. The accessor must be an accessor functor. See {`bdlat_typecategory`|`ACCESSOR` Functors} for the requirements on `accessor`. The behavior is undefined unless `0 <= index < bdlat_ArrayFunctions::size(array)`.

== Return Value

value from the invocation of `accessor`

== Parameters

[cols="1,4"]
|===
| Name| Description
| *array*
| array whose element is accessed
| *accessor*
| functor applied to the element with a category tag
| *index*
| zero‐based index of the element
|===


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