Boost container attributes and comparison with standard library implementations

sizeof comparison across major implementations
String Small String Optimization (SSO) comparison across major implementation
deque implementation block/segment size comparison
sizeof value of Boost.Container containers

`sizeof` comparison across major implementations

These two tables compare sizeof(container) across major implementations and Boost.Container.

Table 7.2. sizeof comparison in 32/64 bit systems

Container	Boost.Container	libstdc++ (GCC)	libc++ (Clang)	Microsoft STL ^[a]
`vector`	12 / 24	12 / 24	12 / 24	12 / 24
`deque`	16 / 32	40 / 80	24 / 48	20 / 40
`list`	12 / 24	12 / 24	12 / 24	8 / 16
`multi_set/map`	16 / 32	24 / 48	12 / 24	8 / 16
`string` ^[b]	12 / 24	24 / 32	12 / 24	24 / 32
^[a] Uses heap-allocated sentinels for `list` and `[multi_]set/map`, resulting in a smaller `sizeof` but requiring allocation on construction. ^[b] Boost.Container has a SSO size option (`inline_chars`) that changes the `sizeof`. The number shown is the `sizeof` for the default SSO size

String Small String Optimization (SSO) comparison across major implementation

This tables shows the number of characters (excluding the null terminator) that can be hold inline across major implementations and Boost.Container.

Table 7.3. SSO capacity for string

Mode	Boost.Container ^[a]	libstdc++ (GCC)	libc++ (Clang)	Microsoft STL
32 bit	10	15	10	15
64 bit	22	15	22	15
^[a] Boost.Container has a SSO size selection (up to 127 characters) option called `inline_chars`

`deque` implementation block/segment size comparison

deque implementations are based on a segmented array of blocks, and the block size is an important parameter that affects performance. This table shows the block size in bytes for deque implementations across major implementations and Boost.Container.

Table 7.4. Deque Block Sizes

Implementation	Block Size in bytes
Boost.Container	512 (32-bit) / 1024 (64-bit) ^[a]
libstdc++ (GCC)	512
libc++ (Clang)	4096
Microsoft STL	16
^[a] `deque` & `segtor` have an option to select the `block_size`

`sizeof` value of Boost.Container containers

Table 7.5. sizeof comparison between Boost Containers (in bytes) This table shows the sizeof value of Boost.Container containers in 32 and 64 bit systems. Note that these values can be changed by configuration options (like stored_size) so they are shown here for the default configuration.

Container	32-bit	64-bit
`vector`	12	24
`deque`	16	32
`devector`	16	32
`segtor`	12	24
`stable_vector`	20	40
`list`	12	24
`slist`	8	16
`map/set`	16	32
`flat_[multi_]map/set` ^[a]	12	24
`string`	12	24
^[a] `boost::containter::flat_xxx` containers are by default ordered `vector`s, but these containers can be configure to use another container as the underlying sequence

Boost C++ Libraries