[#BloombergLP-bslstl-Variant_TypeToIndex-0d]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::Variant_TypeToIndex
:relfileprefix: ../../
:mrdocs:

Compute the zero‐based index of `t_TYPE` in `t_VARIANT`'s alternatives.

== Synopsis

Declared in `<bslstl_variant.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_TYPE,
    class t_VARIANT>
struct Variant_TypeToIndex;
----

== Description

This component‐private metafunction calculates the zero‐based index of (template parameter) `t_TYPE` in the list of alternatives in (template parameter) `t_VARIANT`, or `bsl::variant_npos` if there is no such alternative.

The primary template (used when `t_VARIANT` is not a `bsl::variant`) is not defined.

== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/Variant_TypeToIndex-00.adoc[`Variant_TypeToIndex<t_TYPE, bsl::variant<t_HEAD, t_TAIL...>>`] 
| Compute the zero‐based index of `t_TYPE` in a `bsl::variant`.
|===



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