switch and Choosing a Branch Style

switch: choosing among discrete values

switch (command) {
    case 'h':
        print_help();
        break;
    case 'q':
        quit = true;
        break;
    default:
        std::cout << "unknown command\n";
        break;
}

switch compares one integral or enum value against case labels. It reads better than a long if/else if chain when the tests are all equality against constants.

The fall-through trap (and the one legit use)

Without break, execution falls through into the next case:

case 1:
    std::cout << "one";
    // NO break — also prints "two"!
case 2:
    std::cout << "two";
    break;

GCC warns about accidental fall-through (-Wimplicit-fallthrough with -Wextra). The one legitimate use — shared code for several cases — must be an explicit [[fallthrough]]; comment-attribute so reviewers know it is intended. Beginners: always break;.

switch vs if/else — how to choose

• Equality against a fixed set of constants (char command, int menu, enum class state) → switch.
• Ranges, compound logic, std::string comparisons → if/else.
• (switch on std::string does not work; if/else with == does.)

One-liners: the conditional operator

std::string label = (score >= 50) ? "pass" : "fail";

cond ? a : b is an expression — useful for initializing a variable from a tiny choice. Anything hairier belongs in a real if.

Coming up

Conditions decide once; loops decide a thousand times. Next module: repetition.