---
name: "__gnu_pbds::detail::maybe_null_type"
section: "3cxx"
platform: "linux"
package: "libstdc++-12-doc"
version: "12.4.0-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/__gnu_pbds::detail::maybe_null_type/3cxx"
---

# \_\_gnu\_pbds::detail::maybe\_null\_type(3cxx)

Base class for conditionally defining a static data member.

## NAME

\_\_gnu\_pbds::detail::maybe\_null\_type\< Key, Mapped, \_Alloc, Store\_Hash \> - Base class for conditionally defining a static data member.

## SYNOPSIS

`#include <types_traits.hpp>`

Inherited by **\_\_gnu\_pbds::detail::types\_traits\< Key, Mapped, \_Alloc, false \>**, and **\_\_gnu\_pbds::detail::types\_traits\< Key, Mapped, \_Alloc, Store\_Hash \>**.

## Detailed Description

### template\<typename Key, typename Mapped, typename \_Alloc, bool Store\_Hash\>

struct \_\_gnu\_pbds::detail::maybe\_null\_type\< Key, Mapped, \_Alloc, Store\_Hash \>"Base class for conditionally defining a static data member.

## Author

Generated automatically by Doxygen for libstdc++ from the source code.