switch – no break

If in a switch statement a case alternative does not end with a break, the statements associated with all subsequent cases are executed until a break is found. Given an int variable: 
int a;
the switch statement below checks a’s value. If it is 3, the statement associated with it is executed and since there is no break the statement associated with case 4 is executed; at which point a break is found and the switch is exited. If a’s value is 1, the statements associated with it would be executed and since there are none and there is no break the statement associated with case 2 is executed; at which point a break is found and the switch is exited. If a’s value is 2 or 4 or does not match either 1, 2, 3, or 4, the switch reserves no surprises. 
switch(a)
{
case 1:
case 2:
     cout << "you entered either 1 or 2";
     break;
case 3:
     cout << "you entered 3\n";
case 4:
     cout << "you entered either 4 or 3\n";
           break;
default:
     cout << "you did not enter either 1, 2, 3 or 4";
}
A working example follows.

Example


#include <iostream>
using namespace std;

int main()
{   
     cout << "Enter a value, please ";
     int a;
     cin >> a;

     switch(a)
     {
     case 1:
     case 2:
           cout << "you entered either 1 or 2";
           break;
     case 3:
           cout << "you entered 3\n";
     case 4:
           cout << "you entered either 4 or 3\n";
                break;
     default:
           cout << "you did not enter either 1, 2, 3 or 4";
     }
}

Output with input equal to 1

Enter a value, please 1
you entered either 1 or 2

Output with input equal to 3

Enter a value, please 3
you entered 3
you entered either 4 or 3