[#llvm-capacity_in_bytes-00]
= xref:llvm.adoc[llvm]::capacity_in_bytes
:relfileprefix: ../
:mrdocs:

Return the approximate size in bytes of the MapVector `X.`

== Synopsis

Declared in `<llvm/ADT/MapVector.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename KeyT,
    typename ValueT,
    typename MapType = xref:llvm/DenseMap-0c.adoc[DenseMap<KeyT, unsigned int>],
    typename VectorType = xref:llvm/SmallVector-06.adoc[SmallVector<std::pair<KeyT, ValueT>, 0>],
    unsigned int N = 0>
[[nodiscard]]
size_t
capacity_in_bytes(xref:llvm/MapVector-04b.adoc[MapVector<KeyT, ValueT, MapType, VectorType, N>] const& X);
----

== Return Value

Approximate size in bytes of `X's` storage.

[NOTE]
====
The return value https://en.cppreference.com/cpp/language/attributes/nodiscard[should not be discarded^].
====
== Parameters

[cols="1,4"]
|===
| Name| Description
| *X*
| MapVector whose storage size is queried.
|===


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