clang-tidy - abseil-duration-division — Extra Clang Tools 8 documentation

# Extra Clang Tools 8 documentation

## clang-tidy - abseil-duration-division

# abseil-duration-division

`absl::Duration` arithmetic works like it does with integers. That means that division of two `absl::Duration` objects returns an `int64` with any fractional component truncated toward 0. See this link for more information on arithmetic with `absl::Duration`.

For example:

    absl::Duration d = absl::Seconds(3.5);
    int64 sec1 = d / absl::Seconds(1);     // Truncates toward 0.
    int64 sec2 = absl::ToInt64Seconds(d);  // Equivalent to division.
    assert(sec1 == 3 && sec2 == 3);

    double dsec = d / absl::Seconds(1);  // WRONG: Still truncates toward 0.
    assert(dsec == 3.0);

If you want floating-point division, you should use either the `absl::FDivDuration()` function, or one of the unit conversion functions such as `absl::ToDoubleSeconds()`. For example:

    absl::Duration d = absl::Seconds(3.5);
    double dsec1 = absl::FDivDuration(d, absl::Seconds(1));  // GOOD: No truncation.
    double dsec2 = absl::ToDoubleSeconds(d);                 // GOOD: No truncation.
    assert(dsec1 == 3.5 && dsec2 == 3.5);

This check looks for uses of `absl::Duration` division that is done in a floating-point context, and recommends the use of a function that returns a floating-point value.