Chapter 2

Question 1

assignment operator

Answer 1

= is Python’s assignment operator, which should not be confused with the mathematical comparison operator using the same symbol.

Question 2

assignment statement

Answer 2

A statement that assigns a value to a name (variable). To the left of the assignment operator, =, is a name. To the right of the assignment operator is an expression which is evaluated by the Python interpreter and then assigned to the name. The difference between the left and right hand sides of the assignment statement is often confusing to new programmers. In the following assignment:

n = n + 1
n plays a very different role on each side of the =. On the right it is a value and makes up part of the expression which will be evaluated by the Python interpreter before assigning it to the name on the left.

Question 3

comment

Answer 3

Information in a program that is meant for other programmers (or anyone reading the source code) and has no effect on the execution of the program.

Question 4

composition

Answer 4

The ability to combine simple expressions and statements into compound statements and expressions in order to represent complex computations concisely.

Question 5

concatenate

Answer 5

To join two strings end-to-end.

Question 6

data type

Answer 6

A set of values. The type of a value determines how it can be used in expressions. So far, the types you have seen are integers (type int), floating-point numbers (type float), and strings (type str).

Question 7

evaluate

Answer 7

To simplify an expression by performing the operations in order to yield a single value.

Question 8

expression

Answer 8

A combination of variables, operators, and values that represents a single result value.

Question 9

float

Answer 9

A Python data type which stores floating-point numbers. Floating-point numbers are stored internally in two parts: a base and an exponent. When printed in the standard format, they look like decimal numbers. Beware of rounding errors when you use floats, and remember that they are only approximate values.

Question 10

int

Answer 10

A Python data type that holds positive and negative whole numbers.

Question 11

integer division

Answer 11

An operation that divides one integer by another and yields an integer. Integer division yields only the whole number of times that the numerator is divisible by the denominator and discards any remainder.

Question 12

keyword

Answer 12

A reserved word that is used by the compiler to parse program; you cannot use keywords like if, def, and while as variable names.

Question 13

operand

Answer 13

One of the values on which an operator operates.

Question 14

operator

Answer 14

A special symbol that represents a simple computation like addition, multiplication, or string concatenation.

Question 15

rules of precedence

Answer 15

The set of rules governing the order in which expressions involving multiple operators and operands are evaluated.

Question 16

state diagram

Answer 16

A graphical representation of a set of variables and the values to which they refer.

Question 17

statement

Answer 17

An instruction that the Python interpreter can execute. Examples of statements include the assignment statement and the print statement.

Question 18

str

Answer 18

A Python data type that holds a string of characters.

Question 19

value

Answer 19

A number or string (or other things to be named later) that can be stored in a variable or computed in an expression.

Question 20

variable

Answer 20

A name that refers to a value.

Question 21

variable name

Answer 21

A name given to a variable. Variable names in Python consist of a sequence of letters (a..z, A..Z, and _) and digits (0..9) that begins with a letter. In best programming practice, variable names should be chosen so that they describe their use in the program, making the program self documenting.