Switch Case in Dart

Switch Case In Dart

In this tutorial, you will learn to use dart switch case to control your program’s flow. A Switch case is used to execute the code block based on the condition.

switch(expression) {
    case value1:
        // statements
        break;
    case value2:
        // statements
        break;
    case value3:
        // statements
        break;
    default:
       // default statements
}

How does switch-case statement work in dart

  • The expression is evaluated once and compared with each case value.
  • If expression matches with case value1, the statements of case value1 are executed. Similarly, case value 2 will be executed if the expression matches case value2. If the expression matches the case value3, the statements of case value3 are executed.
  • The break keywords tell dart to exit the switch statement because the statements in the case block are finished.
  • If there is no match, default statements are executed.
Info

Note: You can use a Switch case as an alternative to the if-else-if condition.

Replace If Else If With Switch In Dart

Here you can see the same program using if else if and switch in dart.

Example Using If Else If

This example prints the day name based on the numeric day of the week using a if else if.

void main(){
   var dayOfWeek = 5;
if (dayOfWeek == 1) {
        print("Day is Sunday.");
  }
else if (dayOfWeek == 2) {
       print("Day is Monday.");
     }
else if (dayOfWeek == 3) {
      print("Day is Tuesday.");
     }
else if (dayOfWeek == 4) {
        print("Day is Wednesday.");
     }
else if (dayOfWeek == 5) {
        print("Day is Thursday.");
   }
else if (dayOfWeek == 6) {
        print("Day is Friday.");
    }
else if (dayOfWeek == 7) {
        print("Day is Saturday.");
}else{
        print("Invalid Weekday.");
     }
 }

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Example Of Switch Statement

This example prints the day name based on the numeric day of the week using a switch case.

void main() {
  var dayOfWeek = 5;
  switch (dayOfWeek) {
    case 1:
        print("Day is Sunday.");
        break;
    case 2:
        print("Day is Monday.");
      break;
    case 3:
      print("Day is Tuesday.");
      break;
    case 4:
        print("Day is Wednesday.");
      break;
    case 5:
        print("Day is Thursday.");
      break;
    case 6:
        print("Day is Friday.");
      break;
    case 7:
        print("Day is Saturday.");
      break;
    default:
        print("Invalid Weekday.");
      break;
  }
}

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Info

Note: The syntax of switch statements is cleaner and much easier to read and write.

Switch Case On Strings

You can also use a switch case with strings. This program prints information based on weather value.

void main() {
 const weather = "cloudy";

  switch (weather) {
    case "sunny":
        print("Its a sunny day. Put sunscreen.");
        break;
    case "snowy":
        print("Get your skis.");
      break;
    case "cloudy":
    case "rainy": 
      print("Please bring umbrella.");
      break;
    default:
        print("Sorry I am not familiar with such weather.");
      break;
  }
}

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Switch Case On Enum

An enum or enumeration is used for defining value according to you. You can define your own type with a finite number of options. Here is the syntax for defining enum.

Syntax

enum enum_name { 
  constant_value1, 
  constant_value2, 
  constant_value3 
  }

Example of Switch Using Enum In Dart

Enum plays well with switch statements. Let’s see an example using enum.

// define enum outside main function
enum Weather{ sunny, snowy, cloudy, rainy}
// main method
void main() {
 const weather = Weather.cloudy;
  
  switch (weather) {
    case Weather.sunny:
        print("Its a sunny day. Put sunscreen.");
        break;
    case Weather.snowy:
        print("Get your skis.");
      break;
    case Weather.rainy:
    case Weather.cloudy:
      print("Please bring umbrella.");
      break;
    default:
        print("Sorry I am not familiar with such weather.");
      break;
  }
}

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Video

Watch our video on the switch case in Dart.