switch Statement in C++

 

The switch statement is a control statement that allows you to select one of many code blocks to be executed. It is a better alternative than using multiple if-else statements when you have several possible values for a variable.

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1️⃣ Syntax of switch Statement

switch (expression) {
    case value1:
        // Code to execute if expression == value1
        break;
    case value2:
        // Code to execute if expression == value2
        break;
    case value3:
        // Code to execute if expression == value3
        break;
    default:
        // Code to execute if no case matches
}

Key Points:

• The expression is usually a variable or constant.
• The case values are the possible values that expression can match.
• The break statement is used to exit the switch statement after a match is found. If you omit break, the program will "fall through" and execute the code for the next case.
• The default case is optional and executes if no case matches the expression.

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2️⃣ Example: Simple switch Statement

#include <iostream>
using namespace std;

int main() {
    int day;
    cout << "Enter a number (1-7) for the day of the week: ";
    cin >> day;

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

    return 0;
}

Output:

Enter a number (1-7) for the day of the week: 3
Wednesday

📌 If you input a number outside 1-7, it will print "Invalid day number!" due to the default case.

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3️⃣ Example: Using switch to Choose a Menu Option

#include <iostream>
using namespace std;

int main() {
    int choice;
    cout << "Enter your choice (1-3):\n";
    cout << "1. Add\n";
    cout << "2. Subtract\n";
    cout << "3. Multiply\n";
    cout << "Choice: ";
    cin >> choice;

    switch (choice) {
        case 1:
            cout << "You chose Add." << endl;
            break;
        case 2:
            cout << "You chose Subtract." << endl;
            break;
        case 3:
            cout << "You chose Multiply." << endl;
            break;
        default:
            cout << "Invalid choice!" << endl;
    }

    return 0;
}

Output 1 (if input is 2):

You chose Subtract.

Output 2 (if input is 5):

Invalid choice!

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4️⃣ Example: Switch with Multiple Cases for the Same Block

In some situations, you may want multiple case values to execute the same code. You can simply list them one after another, without break statements between them.

#include <iostream>
using namespace std;

int main() {
    int grade;
    cout << "Enter your grade (A-D): ";
    cin >> grade;

    switch (grade) {
        case 'A':
        case 'B':
            cout << "You passed!" << endl;
            break;
        case 'C':
        case 'D':
            cout << "You need to improve." << endl;
            break;
        default:
            cout << "Invalid grade!" << endl;
    }

    return 0;
}

Output 1 (if input is A):

You passed!

Output 2 (if input is C):

You need to improve.

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5️⃣ Example: Switch with Expressions (Not Just Constants)

You can use a switch statement with expressions, but the expression must be constant or evaluated at compile-time.

#include <iostream>
using namespace std;

int main() {
    int a = 3;
    int b = 4;

    switch (a + b) {
        case 7:
            cout << "The sum is 7!" << endl;
            break;
        case 10:
            cout << "The sum is 10!" << endl;
            break;
        default:
            cout << "The sum is neither 7 nor 10." << endl;
    }

    return 0;
}

Output:

The sum is 7!

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6️⃣ Important Points to Remember About switch

• switch works best when you have multiple conditions that depend on the same variable.
• No need for else, as switch handles multiple conditions on its own.
• break statement: Without break, execution continues to the next case (fall-through).
• default case: It's optional, but good practice to handle unexpected values.

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7️⃣ switch vs if-else

• switch is better when comparing one variable against multiple constant values (e.g., days of the week, menu options).
• if-else is better when checking for more complex conditions (e.g., ranges, multiple variables).

Would you like an example where switch is used with more complex conditions or user input validation?