🎓 A1Learner
🔍
0 of 40 lessons completed

C++ Switch

A switch statement matches one value against a list of cases. The case that matches the value runs its code.

Matching one case

The value 3 matches case 3. That case prints its day name, and its break ends the switch.

#include <iostream>

int main() {
  int day = 3;
  switch (day) {
    case 1:
      std::cout << "Monday" << std::endl;
      break;
    case 2:
      std::cout << "Tuesday" << std::endl;
      break;
    case 3:
      std::cout << "Wednesday" << std::endl;
      break;
    case 4:
      std::cout << "Thursday" << std::endl;
      break;
  }
  return 0;
}

Missing break runs the next case

Case 2 has no break in this program. The run continues into case 3, so its line prints too.

#include <iostream>

int main() {
  int day = 2;
  switch (day) {
    case 1:
      std::cout << "Monday" << std::endl;
      break;
    case 2:
      std::cout << "Tuesday" << std::endl;
    case 3:
      std::cout << "Wednesday" << std::endl;
      break;
  }
  return 0;
}

Default catches the rest

The value 9 matches no case here. The default case runs and prints its line.

#include <iostream>

int main() {
  int day = 9;
  switch (day) {
    case 1:
      std::cout << "Monday" << std::endl;
      break;
    case 2:
      std::cout << "Tuesday" << std::endl;
      break;
    default:
      std::cout << "Unknown day" << std::endl;
      break;
  }
  return 0;
}

Example

#include <iostream>

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

Key points

  • Each case names a value to match against the switch value.
  • break ends a case so the next case does not run.
  • A case runs the lines between its label and its break.
  • The default case runs when no case matches.
  • A switch fits a value with a small set of named cases.

In this example, day holds 6. The switch tests the value against each case in order. Case 6 is the match, so its line prints the day name Saturday. Its break then ends the switch.

Note

Without break, a matched case runs the next case as well.

Try it Yourself

Edit the code, then press Run.

Running is simulated

Exercise

What does break do at the end of a case?