1.. title:: clang-tidy - abseil-duration-division
2
3abseil-duration-division
4========================
5
6``absl::Duration`` arithmetic works like it does with integers. That means that
7division of two ``absl::Duration`` objects returns an ``int64`` with any fractional
8component truncated toward 0. See `this link <https://github.com/abseil/abseil-cpp/blob/29ff6d4860070bf8fcbd39c8805d0c32d56628a3/absl/time/time.h#L137>`_ for more information on arithmetic with ``absl::Duration``.
9
10For example:
11
12.. code-block:: c++
13
14 absl::Duration d = absl::Seconds(3.5);
15 int64 sec1 = d / absl::Seconds(1);     // Truncates toward 0.
16 int64 sec2 = absl::ToInt64Seconds(d);  // Equivalent to division.
17 assert(sec1 == 3 && sec2 == 3);
18
19 double dsec = d / absl::Seconds(1);  // WRONG: Still truncates toward 0.
20 assert(dsec == 3.0);
21
22If you want floating-point division, you should use either the
23``absl::FDivDuration()`` function, or one of the unit conversion functions such
24as ``absl::ToDoubleSeconds()``. For example:
25
26.. code-block:: c++
27
28 absl::Duration d = absl::Seconds(3.5);
29 double dsec1 = absl::FDivDuration(d, absl::Seconds(1));  // GOOD: No truncation.
30 double dsec2 = absl::ToDoubleSeconds(d);                 // GOOD: No truncation.
31 assert(dsec1 == 3.5 && dsec2 == 3.5);
32
33
34This check looks for uses of ``absl::Duration`` division that is done in a
35floating-point context, and recommends the use of a function that returns a
36floating-point value.
37