288: Mainline

Because a conditional-operator expression, unlike an if statement, produces a value, you can place it inside another expression. In the following, for example, a conditional-operator expression appears inside an output expression, solving the duplication problem encountered in Segment 285:

#include  
main ( ) { 
  int change; 
  cin >> change; 
  cout << "The temperature has changed by " 
       << change 
       << (change == 1 ? " degree" : " degrees") 
       << endl; 
} 
--- Data ---
1 
--- Result --- 
The temperature has changed by 1 degree 

If the change is 1 degree, the value returned by the Boolean expression, and displayed, is "degree"; otherwise, the value returned, and displayed, is "degrees".

Note that the parentheses surrounding the Boolean expression are absolutely necessary, because the output operator has precedence higher than that of the conditional operator.