switch 语句

The switch statement allows replacing long chains of if-else if-else statements when comparing a variable against several constant values.

The switch Syntax

The switch statement compares an expression against multiple case labels:

char grade = 'B';

switch (grade) {
    case 'A':
        std::cout << "Excellent!" << std::endl;
        break;
    case 'B':
        std::cout << "Very well!" << std::endl;
        break;
    case 'C':
        std::cout << "Sufficient." << std::endl;
        break;
    default:
        std::cout << "Invalid grade." << std::endl;
        break;
}

• break: is fundamental. If omitted, execution will fall through into the next cases (a behavior known as fall-through).
• default: an optional block executed if none of the previous cases match the tested value.

Try it yourself