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Table of Contents
Basic structure: How to write a switch case
Practical application: When should I use switch instead of if else
Notes: Common Errors and Pit Avoidance Guide
Home Backend Development C++ C switch case example

C switch case example

Jul 12, 2025 am 02:19 AM
c++

The switch case of C is more suitable for handling multiple fixed value branches. The basic structure includes integer variables in switch brackets, constant expressions after each case and corresponding execution code. Finally, default can be added to deal with unmatched cases. Note when using: 1. The variable type must be an integer after switch; 2. It must be a constant after each case; 3. The lack of break will cause a "penetration" error; 4. Braces must be added when defining variables. In practical applications, switch is clearer and more efficient than if else, and is suitable for menu selection, status code processing and other scenarios.

C switch case example

When writing a switch case statement for C, many people will think that it is similar to if else at first, but in fact it is more suitable for handling branch judgments with multiple fixed values. Using it well can make your code clearer and more efficient.

C switch case example

Basic structure: How to write a switch case

The switch statement of C is used to test whether a variable is equal to one of multiple values, each value corresponding to a case branch. Finally, a default branch is usually added as a guarantee.

C switch case example
 int day = 2;
switch (day) {
    case 1:
        cout << "Monday";
        break;
    case 2:
        cout << "Tuesday";
        break;
    case 3:
        cout << "Wednesday";
        break;
    default:
        cout << "Invalid day";
}

A few points to note:

  • The variable type in the brackets after switch must be an integer (such as int , char , not a floating point number).
  • Each case must be followed by a constant expression, not a variable.
  • Without break , the next case will continue to be executed, which is called "fall-through". Sometimes it will be used intentionally, but in most cases it is prone to errors.

Practical application: When should I use switch instead of if else

When you encounter multiple fixed value judgments, such as menu selection, status code processing, and enumeration value judgment, it is more appropriate to use switch .

C switch case example

For example: User input number selection operation:

 int choice;
cout << "Enter your choice (1-3): ";
cin >> choice;

switch (choice) {
    case 1:
        cout << "You selected New Game\n";
        break;
    case 2:
        cout << "You selected Load Game\n";
        break;
    case 3:
        cout << "You selected Exit\n";
        break;
    default:
        cout << "Invalid choice\n";
}

In this case, it can be implemented with if else , but the code will appear lengthy and the logic will not be as intuitive as switch .


Notes: Common Errors and Pit Avoidance Guide

  • Forgot to write break : This is one of the most common mistakes. If a case does not have a break, the program will continue to execute the contents of the next case.

     switch (value) {
        case 1:
            cout << "One"; // No break
        case 2:
            cout << "Two"; // It will also be executed here}
  • case is not followed by a constant : for example case x: is not allowed, x must be a constant or a literal.

  • default is optional but recommended to add : Although syntax is not mandatory, for robustness, it is best to add cases where unexpected values ??are handled.

  • Braces can be omitted : If you define a variable after each case, you need to add {} yourself, otherwise an error will be reported in the compilation.

     case 1:
        int x = 10; // Error cout << x;

    Correct writing:

     case 1: {
        int x = 10;
        cout << x;
        break;
    }

    Basically that's it. By mastering the basic structure and several common problems, you can flexibly use switch case in the appropriate scenario.

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