C - 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.


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

switch(expression) {

   case constant-expression  :
      break; /* optional */
   case constant-expression  :
      break; /* optional */
   /* you can have any number of case statements */
   default : /* Optional */

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.

Flow Diagram

switch statement in C


#include <stdio.h>
int main () {

   /* local variable definition */
   char grade = 'B';

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