Boolean Variables

As usual, for every type of value, there is a corresponding type of variable. In C++ the boolean type is called bool . Boolean variables work just like the other types:

bool bStore;

bStore = true;

bool bTestResult = false;

The first line is a simple variable declaration; the second line is an assignment, and the third line is a combination of a declaration and as assignment, called an initialization.

As I mentioned, the result of a comparison operator is a boolean, so you can store it in a bool variable:

bool bEvenFlag = ( iN % 2 == 0 ); // true if iN is even

bool bPositiveFlag = ( dX > 0 ); // true if dX is positive

and then use it as part of a conditional statement later:

if ( bEvenFlag)

{

ShowText ( "iN was even when I checked it" );

}

A variable used in this way is called a flag, since it flags the presence or absence of some condition.

Note: As with the char type, boolean variables are actually stored as integers, 0 for false and 1 for true. It is not recommended to use other than boolean operators on these variables, however, because the results may be unpredictable.