fall through

v. (n. `fallthrough', var. `fall-through') 1. To exit a loop by exhaustion, i.e., by having fulfilled its exit condition rather than via a break or exception condition that exits from the middle of it. This usage appears to be *really* old, dating from the 1940s and 1950s. 2. To fail a test that would have passed control to a subroutine or some other distant portion of code. 3. In C, `fall-through' occurs when the flow of execution in a switch statement reaches a `case' label other than by jumping there from the switch header, passing a point where one would normally expect to find a `break'. A trivial example switch (color) { case GREEN do_green(); break; case PINK do_pink(); /* FALL THROUGH */ case RED do_red(); break; default do_blue(); break; } The variant spelling `/* FALL THRU */' is also common. The effect of this code is to `do_green()' when color is `GREEN', `do_red()' when color is `RED', `do_blue()' on any other color other than `PINK', and (and this is the important part) `do_pink()' *and then* `do_red()' when color is `PINK'. Fall-through is considered harmful by some, though there are contexts (such as the coding of state machines) in which it is natural; it is generally considered good practice to include a comment highlighting the fall-through where one would normally expect a break.