`switch` — C++ Keyword

`switch` — C++ Keyword

The switch keyword in C++: selects among multiple execution paths based on an integral value.

How to use this reference page

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Scan the top of the page first to identify the primary types, functions, or algorithm families involved.
Use the nearby-page links when your question is really about a companion header, related algorithm family, or broader subsystem.
Validate tricky behavior with a small compileable example before relying on memory for details like invalidation, ordering, allocation, or lifetime rules.

`switch`

Selects among multiple execution paths based on the value of an integral or enumeration expression.

Syntax

switch (expression) {
    case constant1: statements; break;
    case constant2: statements; break;
    default: statements;
}

switch (init-statement; expression) { ... }  // C++17 init-statement form

Example

#include <print>

int main() {
    int day = 3;

    switch (day) {
        case 1: std::println("Monday");    break;
        case 2: std::println("Tuesday");   break;
        case 3: std::println("Wednesday"); break;   // executed
        case 4: std::println("Thursday");  break;
        case 5: std::println("Friday");    break;
        default: std::println("Weekend");
    }
}

Notes

The condition must be an integral or unscoped enumeration type.
Without break, execution falls through to the next case.
Multiple case labels may share one body (implicit fall-through for grouping).
Use [[fallthrough]] to document intentional fall-through.
cppreference: switch

Example in practice

int main() {
    // Pick one facility from this reference page.
    // Write the smallest program that exercises its main precondition,
    // complexity rule, or lifetime constraint before scaling up.
    return 0;
}