Boolean Expressions

Boolean is a value that is either true or false - for example, a boolean variable like rainy might contain either true or false.

An expression is a collection of values and operations that produce a value.  A boolean expression is an expression that produces either true or false as a result.

Boolean expressions appear in if(....) commands - inside the parentheses.  This is usually simple, but using and (&&) operators and or (||) operators produces complex expressions.

Assuming that a=4 , b=6 and c=8 , decide the value of each boolean expression below.

        int  a=4 , b=6 , c=8;

        boolean  pythagoras = ( a*a + b*b == c*c );    // true or false?
        boolean  digits  =  ( a<10  &&  b<10  &&  c<10);                
        boolean  bad  =  (2*b - c+a == 0);                    
        boolean  good =  ( a%2 == 0  ||  b%4 == 0  ||  c%8 == 0 ) ;
        boolean  inOrder = ( a < b  &&  b < c  &&  c < (a+b) );

Solution

       pythagoras == false    16 + 36 = 52, but 8*8 = 64, so not equal

       digits  ==  true            yes, all three numbers are below 10

       bad  ==  false             2*6 - 4 + 8 = 12 - 4 + 8 = 16, not zero

       good ==  true             true || false || true = true, only need 1 true

       inOrder == true          4 < 6  and  6 < 8  and  8 < 10, all true