Thread: terminating input by ctrl+z

How to terminate the input by entering ctrl+z.
I have a sentinel controlled loop that should break when ctrl+z is entered.

Code:

int x=0;

while( condition )
{
     cin >> x;
     do something
}

what's the condition

Ok if I have a situation like this.

Code:

for ( ;; )
{
     cin >> x;
     if ( condition )
          break;
     cin >> y;
     ........
}

what could that condition be: if ( cin )?
Thanks for help.