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In C# language, the switch statement allows our program to select from multiple options, where each option is referred to as case, and each case has a specific value.

• The value inside the parenthesis of a switch statement expression is tested for equality against the value of each case.
• The case with a value matching to the value of the switch statement expression is executed.








Note:

At the end of each case, the break statement is a must, or there will be a compile error.






Switch Statement Example


The case with the value matching to the value within parenthesis of switch statement expression is executed.



//C# switch example


using System;

class Switch 
{

public static void Main()
{
	int i=30;

	switch(i)
	{
	case 10:
		Console.WriteLine("value is 10");
		break;
	case 20:
		Console.WriteLine("value is 20");
		break;
	case 30:
		Console.WriteLine("value is 30");
		break;
	default:
		Console.WriteLine("This is default");
		break;
	}
}
}





Output




value is 30


As the break statement is found after the matching case value 30, hence, the control has not executed any statement connected to any cases underneath.





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Switch statement with no matching case


If no matching case value is found then statement connected to the default case is executed, only if the default case is mentioned with the default keyword.



//C# switch example

using System;

public class SwitchEx 
{

public static void Main()
{
	char i='A';

	switch(i)
	{
		case 'B':
		Console.WriteLine("char value is B");
		break;
	case 'E':
		Console.WriteLine("char value is A");
		break;
	case 'D':
		Console.WriteLine("char value is D");
		break;
	default:
		Console.WriteLine("This is default");
		break;
	}
}
}





Output




This is default


Note: A break statement after each case is not mandatory.









Switch statement cases with no break statement give compile errors.


Using the break statement at the end of each case is a must. If there is no break statement connected to any case then a compile error is thrown during the compilation of the program.



//C# switch example


using System;

public class Switch  
{

public static void Main()
{
	int i=2;

	switch(i)
	{
	case 1:
		Console.WriteLine("value is 1");
		break;
	case 2:
		Console.WriteLine("value is 2");
		break;
	case 3:
		Console.WriteLine("value is 3");
	default:
		Console.WriteLine("This is default");
	}
}
}





Output




SwitchEx.cs(21,2): error CS0163: Control cannot fall through from one case label ('case 3:') to anotherS
SwitchEx.cs(23,2): error CS8070: Control cannot fall out of switch from final case label ('default:')


As you can see that the two compile errors are complaining about not being able to fall through the case labels case 3 and default due to the missing break statement.





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