[#mp_units-contains-01b]
= xref:mp_units.adoc[mp_units]::contains
:relfileprefix: ../
:mrdocs:

`contains` overloads

== Synopses

Declared in `<mp‐units/ext/type_traits.h>`

Checks whether the type `T` matches the type of any of the non‐type template arguments `Vs`


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename T,
    auto Vs...>
[[nodiscard]]
consteval
bool
xref:mp_units/contains-0c8.adoc[contains]();
----

[.small]#xref:mp_units/contains-0c8.adoc[_» more..._]#

Checks whether any of the types `Ts` is a specialization of the class template `T`


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    template<typename...> typename T,
    typename... Ts>
[[nodiscard]]
consteval
bool
xref:mp_units/contains-01e.adoc[contains]();
----

[.small]#xref:mp_units/contains-01e.adoc[_» more..._]#

Checks whether any of the types `Ts` is a specialization of the class template `T`


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    template<auto...> typename T,
    typename... Ts>
[[nodiscard]]
consteval
bool
xref:mp_units/contains-0c1.adoc[contains]();
----

[.small]#xref:mp_units/contains-0c1.adoc[_» more..._]#

Checks whether the type `T` is present in the type pack `T1, Ts...`


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename T,
    typename T1,
    typename... Ts>
[[nodiscard]]
consteval
bool
xref:mp_units/contains-0b.adoc[contains]();
----

[.small]#xref:mp_units/contains-0b.adoc[_» more..._]#

== Return Value

* `true` if `T` matches the type of at least one of `Vs`, `false` otherwise
* `true` if at least one of `Ts` is a specialization of `T`, `false` otherwise
* `true` if `T` is the same as `T1` or one of `Ts`, `false` otherwise

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

[cols="1,4"]
|===
| Name| Description
| *T*
| The type to look for among the types of `Vs`
| *Vs*
| The non‐type template arguments whose types are checked against `T`
| *Ts*
| The types to check
| *T1*
| The first type of the pack to search
|===


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