The && operator has a higher precedence than the || operator. Both operators associate from left to right. An expressions containing && or || is evaluated only until truth or falsehood is known. Thus evaluation of the expression (age > 18) && (height > 6) will stop immediately if age > 18 is false (i.e. the entire expression is false) and continue if age > 18 is true (i.e. the entire expression could still be true if the condition height > 6 is true ).

There is another logical operator that is called logical negation. The sign ! is used for this operator. This operand enables a programmer to ‘reverse’ the meaning of a condition. This is a unary operator that has only a single condition as an operand. The operator ! is placed before a condition. If the original condition (without the ! operator) is false then the ! operator before it converts it to true and the statements attached to this are executed.

Look at the following expression

if ( ! (age > 18 ))

cout << “ The age is less than 18”;

Here the cout statement will be executed if the original condition (age > 18) is false because the ! operator before it reverses this false to true.

The truth table for the logical negation operator ( ! ) is given below.

Expression	! Expression
true	false
false	true

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