[#bsl-shared_ptr-0a-2constructor-088]
= xref:bsl.adoc[bsl]::xref:bsl/shared_ptr-0a.adoc[shared_ptr]::shared_ptr
:relfileprefix: ../../
:mrdocs:

Create a `shared_ptr` owning null with a deleter.

== Synopsis

Declared in `<bslstl_sharedptr.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class DELETER>
shared_ptr(
    xref:bsl/nullptr_t-08.adoc[nullptr_t] nullPointerLiteral,
    DELETER deleter,
    xref:BloombergLP/bslma/Allocator.adoc[BloombergLP::bslma::Allocator]* basicAllocator = 0);
----

== Description

Create a shared pointer that reference‐counts the null pointer, and calls the specified `deleter` with a null pointer (i.e., invokes `deleter((ELEMENT_TYPE *)0)`) when the last shared reference is destroyed. The specified `nullPointerLiteral` is not used. Optionally specify a `basicAllocator` to allocate and deallocate the internal representation of the shared pointer (including a copy of `deleter`). If `basicAllocator` is 0, the currently installed default allocator is used. If an exception is thrown when allocating storage for the internal representation, then `deleter((ELEMENT_TYPE *)0)` will be called. The behavior is undefined unless `deleter` can be called with a null pointer, and unless the constructor making a copy of `deleter` does not throw an exception.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *nullPointerLiteral*
| null‐pointer literal (unused; selects this overload)
| *deleter*
| deleter invoked when the last shared reference is released
| *basicAllocator*
| allocator used to supply memory
|===


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