# Boost Bloom Library

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Boost.Bloom provides the class template `boost::bloom::filter` that
can be configured to implement a classical [Bloom filter](https://en.wikipedia.org/wiki/Bloom_filter)
as well as variations discussed in the literature such as block filters, multiblock filters, and more.

```cpp
#include <boost/bloom/filter.hpp>
#include <cassert>
#include <string>

int main()
{
  // Bloom filter of strings with 5 bits set per insertion
  using filter = boost::bloom::filter<std::string, 5>;

  // create filter with a capacity of 1'000'000 **bits**
  filter f(1'000'000);

  // insert elements (they can't be erased, Bloom filters are insert-only)
  f.insert("hello");
  f.insert("Boost");
  //...

  // elements inserted are always correctly checked as such
  assert(f.may_contain("hello") == true);

  // elements not inserted may incorrectly be identified as such with a
  // false positive rate (FPR) which is a function of the array capacity,
  // the number of bits set per element and generally how the boost::bloom::filter
  // was specified
  if(f.may_contain("bye")) { // likely false
    //...
  }
}
```

## Learn about Boost.Bloom

* [Online documentation](https://boost.org/libs/bloom)
* [Some benchmarks](https://github.com/boostorg/boost_bloom_benchmarks)

## Install Boost.Bloom

* [Download Boost](https://www.boost.org/users/download/) and you're ready to go (this is a header-only library requiring no building).
* Using Conan 2: In case you don't have it yet, add an entry for Boost in your `conanfile.txt` (the example requires at least Boost 1.89):
```
[requires]
boost/[>=1.89.0]
```
<ul>If you're not using any compiled Boost library, the following will skip building altogether:</ul>

```
[options]
boost:header_only=True
```
* Using vcpkg: Execute the command
```
vcpkg install boost-bloom
```
* Using CMake: [Boost CMake support infrastructure](https://github.com/boostorg/cmake)
allows you to use CMake directly to download, build and consume all of Boost or
some specific libraries.

## Support

* Join the **#boost** discussion group at [cpplang.slack.com](https://cpplang.slack.com/)
([ask for an invite](https://cppalliance.org/slack/) if you’re not a member of this workspace yet)
* [File an issue](https://github.com/boostorg/bloom/issues)

## Contribute

* [Pull requests](https://github.com/boostorg/bloom/pulls) against **develop** branch are most welcome.
Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](http://www.boost.org/LICENSE_1_0.txt).