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:

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);
}

Rules For Switch Statement

The expression used in a switch statement must not have "float" or "double" datatype.

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.)

Remark: Nested Switch is possible but you cannot declare or initialize any variable in between switch and case.

switch(expression)
{

        /*data_type identifier = constant ; // not allowed*/

          case constant-expression :

                        switch(expression)
                        {

                                /*data_type identifier = constant ; // not allowed*/

                                  case constant-expression :      
                                                      statement(s);
                                                              break; /* optional */
                                                      /* you can have any number of case statements */
                                 default : /* Optional */
                                                      statement(s);
                        }

                                      break; /* optional */
         case constant-expression :
                             statement(s);
                                      break; /* optional */
                              /* you can have any number of case statements */
         default : /* Optional */
                              statement(s);
}