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fall-through (plural fall-throughs)

  1. (programming) In certain programming constructs, the situation where execution passes to the next condition in a list unless explicitly redirected.
    • 1997, Bjarne Stroustrup, The C++ Programming Language: Language Libraries and Design
      It is a good idea to comment the (rare) cases in which a fall-through is intentional so that an uncommented fall-through can be assumed to be an error.
    • 2001, Graham M Seed, Barry J Cooper, An Introduction to Object-Oriented Programming in C++
      If you place default elsewhere, then a break will be required to prevent fall-through.
    • 2008, Nagel et al, Professional C# 2008
      Specifically, it prohibits fall-through conditions in almost all cases.

switch (x) {
case 1:
    printf("Printed when x=1");
case 2:
    printf("Printed when x=2");
case 3:
    printf("Printed when x=2 or x=3");

A case statement in the C programming language containing a fall-through. Because the second case has no "break" at the end, execution will "fall through" to the third case.