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This article mainly explains the "why do not rely on the implicit sinking of switch sentences in C++", the content of the explanation in the article is simple and clear, easy to learn and understand, now please follow the editor's train of thought slowly in depth, together to study and learn why do not rely on the implicit sinking of switch sentences in C++!

ES.78: don't rely on implicit sinking of switch statements

Reason (reason)

Always end a non-empty case with a break. Accidentally leaving out a break is a fairly common bug. A deliberate fallthrough can be a maintenance hazard and should be rare and explicit.

Typically, break is used to abort a non-empty case processing. Accidentally missing a break is usually a mistake. Intentional sinking treatment may bring maintenance risks and should be used less and explicitly.

Example (sample)

Switch (eventType) {

Case Information:

Update_status_bar ()

Break

Case Warning:

Write_event_log ()

/ / Bad-implicit fallthrough

Case Error:

Display_error_window ()

Break

}

Multiple case labels of a single statement is OK:

There is no problem with multiple tags in a statement.

Switch (x) {

Case'asides:

Case'baked:

Case'fags:

Do_something (x)

Break

}

Return statements in a case label are also OK:

There is no problem using the return statement in the case tag:

Switch (x) {case'asides: return 1; case'baked: return 2; case'cages: return 3;}

Exceptions (exception)

In rare cases if fallthrough is deemed appropriate, be explicit and use the [[fallthrough]] annotation:

In rare cases, if you are sure that the sinking treatment is appropriate, you can clearly indicate it using [[fallthrougn]] notation.

Switch (eventType) {

Case Information:

Update_status_bar ()

Break

Case Warning:

Write_event_log ()

[[fallthrough]]

Case Error:

Display_error_window ()

Break

} Note (Note) Enforcement (implementation recommendation)

Flag all implicit fallthroughs from non-empty cases.

Marks all implicit sinking processing from a non-empty case.

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