Answers to chapter 6 review questions

01. What is an expression?

 A: An expressions is a combination of constants, variables, and operators
    which results in a single value.

02. What is an operator?

 A: An operator is a symbol used in source code to specify a specific
    operation.

03. How do expressions get work done in a program?

 A: Expressions manipulate the data by combining, altering, testing, and
    changing it. 

04. What is meant by the "result" of an expression?

 A: The data items of the expression are combined with one or more operators
    to come up with a single value called the result.

05. Describe an arithmetic expression.

 A: An expression that uses arithmetic operators on numeric data.

06. What is the purpose of an arithmetic expression?

 A: To perform an arithmetic calculation producing a numeric result.

07. Describe a relational expression.

 A: An expression that uses relational operators on data.

08. What is the purpose of a relational expression?

 A: To compare the relationships between data items producing a "truth value"
    result.

09. What is a boolean value?

 A: A boolean value is a value that is either true or false.

10. Explain the purpose of the "and" and the "or" operator.

 A: To combine two or more relational expressions to see if both or either
    are true or false.

11. What is precedence?

 A: Precedence is the rule that determines which operator in an expression
    gets evaluated first.

12. What is associativity?

 A: Associativity is the rule that determines in which order the operator
    looks at its operands, and also which operator in an expression
    gets evaluated first when they have the same precedence.

