Logical (Boolean) Operators

There are three logical operators in C++: AND, OR and NOT, which are denoted by the symbols && , || and ! . The semantics (meaning) of these operators is similar to their meaning in English. For example dX > 0 && dX < 10 is true only if dX is greater than zero AND less than 10.

bEvenFlag || iN%3 == 0 is true if either of the conditions is true, that is, if bEvenFlag is true OR the number is divisible by 3.

Finally, the NOT operator has the effect of negating or inverting a bool expression, so !bEvenFlag is true if bEvenFlag is false; that is, if the number is odd.

Logical operators often provide a way to simplify nested conditional statements. For example, it is easy to write the following code:

if ( iX > 0 )

{

if ( iX < 10 )

{

ShowText ( "iX is a positive single digit" );

}

}

using a single conditional:

if ( iX > 0 && iX < 10 )

{

ShowText ( "iX is a positive single digit" );

}