Switch Statements

Switch statements provide a more readable and efficient way to handle multiple conditions compared to using numerous else if statements. They work by evaluating the value of a variable and executing the matching case block.

Syntax

Here is an example of the structure of a switch statement:

switch (integer_expression) {
  case value1:
    // Case actions
    break;
  case value2:
    // Case actions
    break;
  // ...
  default:
}

Note

The default statement is optional.

Caution

Omitting a break statement in a case block causes the program to execute all subsequent case blocks, regardless of their conditions. This behavior, known as fall-through, can lead to unintended results.

However, the break statement is not required in the default case since it is the last block and no further execution follows.

Use Cases

switch statements are particularly useful for menu-driven scenarios, where a user selects an option, and the program executes the corresponding code block. This structure makes the code more organized and easier to manage compared to multiple if-else statements.

// Copyright 2024 CSCE240
#include <iostream>

using std::cin;
using std::cout;
using std::endl;

int main() {
  // Message user
  cout << "Welcome to the Program!" << endl;
  cout << "-----------------------" << endl;
  cout << "Enter 1: To Do This\nEnter 2: To Do That\nEnter 3: To Do "
          "Something\nEnter 4: To Quit"
       << endl;

  // Get user input
  int input;
  cin >> input;

  // Do something
  switch (input) {
    case 1:
      // Do this
      break;
    case 2:
      // Do that
      break;
    case 3:
      // Do something
      break;
    case 4:
      cout << "Goodbye..." << endl;
      break;
    default:
      cout << "Please select one of the allowed options..." << endl;
  }

  return 0;
}

Note

You would want to wrap most of the program in a while loop which will be covered in another section so that it repeats until the user quits.

switch statements can also be useful if you need to return a value when creating functions, which will be covered later. If returning a value, you can omit the break statements.

switch (month) {
  case 1:
    return "January";
  case 2:
    return "February";
  // Cont'd
}

Style Requirements

A full list of style requirements for general control structures applied to switch statements can be found in the control structures page.