[#BloombergLP-bslstl-Function_InvokerUtilNullCheck-09-isNull]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::xref:BloombergLP/bslstl/Function_InvokerUtilNullCheck-09.adoc[Function&lowbar;InvokerUtilNullCheck&lt;bsl::function&lt;PROTO&gt;&gt;]::isNull
:relfileprefix: ../../../
:mrdocs:

Return whether the specified `bsl&colon;&colon;function` is empty&period;

== Synopsis

Declared in `&lt;bslstl&lowbar;function&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
static
bool
isNull(xref:bsl/function-0a.adoc[bsl::function&lt;PROTO&gt;] const& f);
----

== Return Value

`true` if `f` is empty, and `false` otherwise

== Parameters

[cols="1,4"]
|===
| Name| Description
| *f*
| function object to test for emptiness
|===


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