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R - Switch



The Switch statement in R language is used to execute one of many code statements. It can be considered as group of If-else statements.

Syntax

switch (expression, case1, case2, case3, ...)

The switch expression is evaluated and matched with the cases. When the case matches, the following block of code is executed.

Flow Diagram:

R Switch

Example:

In the example below, the switch expression is a variable called i with value 2 which is matched against case values. When the case value matches with expression value, the following block of code is executed.

public class MyClass {
  public static void main(String[] args) {
    int i = 2;
    switch(i){
      case 1: 
         System.out.println("Red");
         break; 
      case 2: 
         System.out.println("Blue");
         break;
      case 3: 
         System.out.println("Green");
         break;
    }  
  }
}

The output of the above code will be:

Blue

default and break statements

Default case and break statement are optional here.

  • Default Case: Default Statement is executed when there is no match between switch expression and test cases.
  • Break Statement: Break statement is used to get out of the Switch statement after a match is found.

Example:

In the example below, the switch expression is a variable called i with value 10 which is matched against case values. When the case value matches with expression value, the following block of code is executed and there is no case with value 10, hence default block of code is executed.

public class MyClass {
  public static void main(String[] args) {
    int i = 10;
    switch(i){
      case 1: 
         System.out.println("Red");
         break; 
      case 2: 
         System.out.println("Blue");
         break;
      case 3: 
         System.out.println("Green");
         break;
      default:
         System.out.println("No match found.");
    }  
  }
}

The output of the above code will be:

No match found.

Please not that, the default statement can be placed at any position in the switch statement. In such instances, add break statement with default statement.

Example:

Consider the example below, where default statement is placed on the top in a switch statement.

public class MyClass {
  public static void main(String[] args) {
    int i = 10;
    switch(i){
      default:
         System.out.println("No match found."); 
         break;
      case 1: 
         System.out.println("Red");
         break; 
      case 2: 
         System.out.println("Blue");
         break;
      case 3: 
         System.out.println("Green");
    }  
  }
}

The output of the above code will be:

No match found.

Common code blocks

There are instances where same code block is required in multiple cases.

Example:

In the example below, same code block is shared for different switch cases.

public class MyClass {
  public static void main(String[] args) {
    int i = 10;
    switch(i){
      case 1: 
         System.out.println("Red");
         break; 
      case 2:
      case 10: 
         System.out.println("Blue");
         break;
      case 3:
      case 4:
      case 5: 
         System.out.println("Green");
    }  
  }
}

The output of the above code will be:

Blue

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