Week 6, Notes 1

Boolean Variables

Variables declared to be of the primitive type boolean may hold one of two values – either true or false

E.g.,

boolean b; // declare a variable to hold a boolean

b = true; // assign the boolean literal value ‘true’ to b

There are two binary and one unary logical operators:

b1 && b2 // true if both b1 and b2 are true, otherwise false

b1 || b2 // false if both b1 and b2 are false, otherwise true

! b1 // true if b1 is false, false if b1 is true

All of the possible inputs and results for these operators are shown in the following table:

Know this table by memory

true != false

the result of this expression is true

the result of this expression is true

The relational operators < and > cannot be applied to boolean operands.

String more than one of a particular operator together, e..g, a = b = c;

Associativity says which one of the operators happens first.

For assignment (=) the rightmost happens first.

For most other operators, the leftmost happens first.

Computers do one thing at a time.

Precedence is determining which operators happen in which order during the evaluation of an expression.

The following table shows the precedence order of operators. (We do not need to know the << and >> operators.)