C++ Switch

The switch Statement

switch is an alternative to a long chain of if-else if. It matches an expression against a list of constant values (case labels).

switch (expression) {
    case value1:
        // code
        break;
    case value2:
        // code
        break;
    default:
        // code if no case matches
}

#include <iostream>
using namespace std;

int main() {
    int day;
    cout << "Enter day (1-7): "; cin >> day;

    switch (day) {
        case 1: cout << "Monday";    break;
        case 2: cout << "Tuesday";   break;
        case 3: cout << "Wednesday"; break;
        case 4: cout << "Thursday";  break;
        case 5: cout << "Friday";    break;
        case 6: cout << "Saturday";  break;
        case 7: cout << "Sunday";    break;
        default: cout << "Invalid day";
    }
    cout << endl;
    return 0;
}

Sample Run:

Enter day (1-7): 5
Friday

break and default

• break — exits the switch block. Without it, execution "falls through" to the next case.
• default — optional, runs when no case matches (like else).

Fall-Through Example

Intentional fall-through lets multiple cases share code:

int month = 4;
switch (month) {
    case 4:
    case 6:
    case 9:
    case 11:
        cout << "30 days" << endl;   // April falls through to here
        break;
    case 2:
        cout << "28 or 29 days" << endl;
        break;
    default:
        cout << "31 days" << endl;
}

Output:

30 days

#include <iostream>
using namespace std;

int main() {
    double a, b;
    char op;
    cout << "Enter: num op num (e.g. 5 + 3): ";
    cin >> a >> op >> b;

    switch (op) {
        case '+': cout << a + b; break;
        case '-': cout << a - b; break;
        case '*': cout << a * b; break;
        case '/':
            if (b != 0) cout << a / b;
            else cout << "Error: divide by zero";
            break;
        default: cout << "Unknown operator";
    }
    cout << endl;
    return 0;
}

Summary

• switch matches an integer/char expression against case values.
• Always use break to prevent unintended fall-through.
• default handles values that match no case.
• Multiple cases can share code by stacking them without break.