[#BloombergLP-bdlb-BitStringUtil-num0]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlb.adoc[bdlb]::xref:BloombergLP/bdlb/BitStringUtil.adoc[BitStringUtil]::num0
:relfileprefix: ../../../
:mrdocs:

Return the number of 0 bits in a range of `bitString`.

== Synopsis

Declared in `<bdlb_bitstringutil.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
static
std::size_t
num0(
    uint64_t const* bitString,
    std::size_t index,
    std::size_t numBits);
----

== Description

Return the number of 0 bits in the specified `numBits` beginning at the specified `index` in the specified `bitString`. The behavior is undefined unless `bitString` has a length of at least `index + numBits`.

== Return Value

count of 0 bits in the examined range

== Parameters

[cols="1,4"]
|===
| Name| Description
| *bitString*
| bit string to examine
| *index*
| starting bit position
| *numBits*
| number of bits to examine
|===


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