Switch Case

From Gemini (Bard)

switch (expression) {
    case value1:
        // code to execute if expression equals value1
        break;
    case value2:
        // code to execute if expression equals value2
        break;
    // ... more case labels
    default:
        // code to execute if expression doesn't match any case
        break;
}

Break Statements

Normally, each case block needs a break at the end, otherwise it will "fall through" to the next block, meaning every case will be visited. break at the end of each case ensures that only one case is visited.

However, you only need a break if the body of the case does not otherwise exit the scope or exit the program. The following eliminate the need for a break statement in a case block:

• return

• CHECK(false) (an assertion or similar that is always false).

• LOG(FATAL)

• exit()

Enum Class and Switch Statements

In newer versions of C++, the compiler can give errors (optional feature) if you run a switch statement and you don't have exactly one case for each enum value.

It's better to not include a default case if this feature is used, because then the compiler will catch such an issue early, whereas otherwise you wouldn't catch it until runtime.