[#BloombergLP-bslmt-Latch-countDown]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslmt.adoc[bslmt]::xref:BloombergLP/bslmt/Latch.adoc[Latch]::countDown
:relfileprefix: ../../../
:mrdocs:

Decrement the number of events that this latch is waiting for by the specified `numEvents`, and if the resulting number of events is 0 release any waiting threads&period; The behavior is undefined unless `numEvents &gt; 0` and the sum of all events that have arrived at this latch does not exceed the count with which it was initialized&period; Note that the initial count of events is supplied at construction&period;

== Synopsis

Declared in `&lt;bslmt&lowbar;latch&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
void
countDown(int numEvents);
----


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