llvm-project/clang-tools-extra/docs/clang-tidy/checks/readability-container-size-...

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.. title:: clang-tidy - readability-container-size-empty
readability-container-size-empty
================================
Checks whether a call to the ``size()`` method can be replaced with a call to
``empty()``.
The emptiness of a container should be checked using the ``empty()`` method
instead of the ``size()`` method. It is not guaranteed that ``size()`` is a
constant-time function, and it is generally more efficient and also shows
clearer intent to use ``empty()``. Furthermore some containers may implement
the ``empty()`` method but not implement the ``size()`` method. Using
``empty()`` whenever possible makes it easier to switch to another container in
the future.
The check issues warning if a container has ``size()`` and ``empty()`` methods
matching following signatures:
.. code-block:: c++
size_type size() const;
bool empty() const;
`size_type` can be any kind of integer type.