Logical Operators: 
They are used to combine two or more conditions/constraints or to complement 
the evaluation of the original condition under consideration. They are 
described below: 
 

Logical AND operator: The ‘&&’ operator returns true when both the conditions 
under consideration are satisfied. Otherwise it returns false. For example, a
&& b returns true when both a and b are true (i.e. non-zero).

Logical OR operator: The ‘||’ operator returns true even if one (or both) of
the conditions under consideration is satisfied. Otherwise it returns false. 
For example, a || b returns true if one of a or b or both are true 
(i.e. non-zero). Of course, it returns true when both a and b are true.

Logical NOT operator: The ‘!’ operator returns true the condition in 
consideration is not satisfied. Otherwise it returns false. For example, 
!a returns true if a is false, i.e. when a=0.