C++ switch statement

In this article, we will learn about c++ switch statement.The C++ switch statement executes one statement from multiple conditions. It is like if-else-if ladder statement in C++.

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.

Below is the structure of switch statement

switch(expression){      
case value1:      
 //code to be executed;      
 break;    
case value2:      
 //code to be executed;      
 break;    
......      
      
default:       
 //code to be executed if all cases are not matched;      
 break;    
}    

C++ switch example

#include <iostream>  
using namespace std;  
int main () {  
       int num;  
       cout<<"Enter a number to check grade:";    
       cin>>num;  
           switch (num)    
          {    
              case 10: cout<<"It is 10"; break;    
              case 20: cout<<"It is 20"; break;    
              case 30: cout<<"It is 30"; break;    
              default: cout<<"Not 10, 20 or 30"; break;    
          }    
    }    

Output:

Enter a number:
10
It is 10

Output:

Enter a number:
55
Not 10, 20 or 30

Another C++ switch 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