switch Statement

A switch Statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each switch case.

Syntax

The syntax for a switch statement in C programming language is as follows −

switch(expression)
	 {
		 case constant-expression  :
	      statement(s);
	      break; /* optional */

		case constant-expression  :
	      statement(s);
	      break; /* optional */

		/* you can have any number of case statements */
	    default : /* Optional */
	    statement(s);
	}

The following rules apply to a switch statement −

• The expression used in a switch statement must have an integral or enumerated type, or be of a class type in which the class has a single conversion function to an integral or enumerated type.

• You can have any number of case statements within a switch. Each case is followed by the value to be compared to and a colon.

• The constant-expression for a case must be the same data type as the variable in the switch, and it must be a constant or a literal.

• When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached.

• When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement.

• Not every case needs to contain a break. If no break appears, the flow of control will fall through to subsequent cases until a break is reached.

• A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.

Example

#include <stdio.h>
	int main ()
	{
	   /* local variable definition */
	   char grade = 'B';

	   switch(grade) {
	      case 'A' :
		 printf("Excellent!\n" );
		 break;
	      case 'B' :
	      case 'C' :
		 printf("Well done\n" );
		 break;
	      case 'D' :
		 printf("You passed\n" );
		 break;
	      case 'F' :
		 printf("Better try again\n" );
		 break;
	      default :
		 printf("Invalid grade\n" );
	   }

	   printf("Your grade is  %c\n", grade );

	   return 0;
	}

When the above code is compiled and executed, it produces the following result −

Well done
Your grade is B