Chapter 2

Question 1

assignment statement

Answer 1

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 token 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 2

assignment token

Answer 2

= is Python’s assignment token. Do not confuse it with equals, which is an operator for comparing values.

Question 3

composition

Answer 3

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

Question 4

concatenate

Answer 4

To join two strings end-to-end.

Question 5

data type

Answer 5

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 (int), floating-point numbers (float), and strings (str).

Question 6

evaluate

Answer 6

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

Question 7

expression

Answer 7

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

Question 8

float

Answer 8

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 9

floor division

Answer 9

An operator (denoted by the token //) that divides one number by another and yields an integer, or, if the result is not already an integer, it yields the next smallest integer.

Question 10

int

Answer 10

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

Question 11

keyword

Answer 11

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 12

modulus operator

Answer 12

An operator, denoted with a percent sign ( %), that works on integers and yields the remainder when one number is divided by another.

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. rules of precedence

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 snapshot

Answer 16

A graphical representation of a set of variables and the values to which they refer, taken at a particular instant during the program’s execution.

Question 17

statement

Answer 17

An instruction that the Python interpreter can execute. So far we have only seen the assignment statement, but we will soon meet the import statement and the for 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.