C++ LANGUAGE SWITCH STATEMENT PAGE 61

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C++ LANGUAGE SWITCH STATEMENT

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 case. 

Syntax 

The syntax for a switch statement in C++ 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 <iostream>
 
using namespace std; 
  
int main () 
{ 
   // local variable declaration: 
   char grade = 'D'; 
 
   switch(grade) 
   { 
   case 'A' : 
      cout << "Excellent!" << endl;  
      break; 
   case 'B' : 
   case 'C' : 
      cout << "Well done" << endl; 
      break; 
   case 'D' : 
      cout << "You passed" << endl; 
      break; 
   case 'F' : 
      cout << "Better try again" << endl; 
      break; 
   default : 
      cout << "Invalid grade" << endl; 
   } 
   cout << "Your grade is " << grade << endl; 
  
   return 0; 
} 
This would produce the following result: 
You passed 
Your grade is D