clang-tidy - bugprone-incorrect-roundings — Extra Clang Tools 12 documentation

# Extra Clang Tools 12 documentation

## clang-tidy - bugprone-incorrect-roundings

# bugprone-incorrect-roundings

Checks the usage of patterns known to produce incorrect rounding. Programmers often use:

    (int)(double_expression + 0.5)

to round the double expression to an integer. The problem with this:

1. It is unnecessarily slow.

2. It is incorrect. The number 0.499999975 (smallest representable float number below 0.5) rounds to 1.0. Even worse behavior for negative numbers where both -0.5f and -1.4f both round to 0.0.