How to Think Like a Computer Scientist

Question 1

activecode

Answer 1

A unique interpreter environment that allows Python to be executed from within a web browser.

Question 2

algorithm

Answer 2

A general step by step process for solving a problem.

Question 3

bug

Answer 3

An error in a program.

Question 4

byte code

Answer 4

An intermediate language between source code and object code. Many modern languages first compile source code into byte code and then interpret the byte code with a program called a virtual machine.

Question 5

codelens

Answer 5

An interactive environment that allows the user to control the step by step execution of a Python program

Question 6

comment

Answer 6

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 7

compile

Answer 7

To translate a program written in a high-level language into a low-level language all at once, in preparation for later execution.

Question 8

debugging

Answer 8

The process of finding and removing any of the three kinds of programming errors.

Question 9

exception

Answer 9

Another name for a runtime error.

Question 10

executable

Answer 10

Another name for object code that is ready to be executed.

Question 11

formal language

Answer 11

Any one of the languages that people have designed for specific purposes, such as representing mathematical ideas or computer programs; all programming languages are formal languages.

Question 12

high-level language

Answer 12

A programming language like Python that is designed to be easy for humans to read and write.

Question 13

interpret

Answer 13

To execute a program in a high-level language by translating it one line at a time.

Question 14

low-level language

Answer 14

A programming language that is designed to be easy for a computer to execute; also called machine language or assembly language.

Question 15

natural language

Answer 15

Any one of the languages that people speak that evolved naturally.

Question 16

object code

Answer 16

The output of the compiler after it translates the program.

Question 17

parse

Answer 17

To examine a program and analyze the syntactic structure.

Question 18

portability

Answer 18

A property of a program that can run on more than one kind of computer.

Question 19

print function

Answer 19

A function used in a program or script that causes the Python interpreter to display a value on its output device.

Question 20

problem solving

Answer 20

The process of formulating a problem, finding a solution, and expressing the solution.

Question 21

program

Answer 21

A sequence of instructions that specifies to a computer actions and computations to be performed.

Question 22

programming language

Answer 22

A formal notation for representing solutions.

Question 23

Python shell

Answer 23

An interactive user interface to the Python interpreter. The user of a Python shell types commands at the prompt (»>), and presses the return key to send these commands immediately to the interpreter for processing.

Question 24

runtime error

Answer 24

An error that does not occur until the program has started to execute but that prevents the program from continuing.

Question 25

semantic error

Answer 25

An error in a program that makes it do something other than what the programmer intended.

Question 26

semantics

Answer 26

The meaning of a program.

Question 27

shell mode

Answer 27

A style of using Python where we type expressions at the command prompt, and the results are shown immediately. Contrast with source code, and see the entry under Python shell.

Question 28

source code

Answer 28

A program, stored in a file, in a high-level language before being compiled or interpreted.

Question 29

syntax

Answer 29

The structure of a program.

Question 30

syntax error

Answer 30

An error in a program that makes it impossible to parse — and therefore impossible to interpret.

Question 31

token

Answer 31

One of the basic elements of the syntactic structure of a program, analogous to a word in a natural language.

Question 32

assignment statement

Answer 32

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 33

assignment token

Answer 33

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

Question 34

class

Answer 34

see data type

Question 35

comment

Answer 35

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 36

data type

Answer 36

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 37

decrement

Answer 37

Decrease by 1.

Question 38

evaluate

Answer 38

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

Question 39

expression

Answer 39

A combination of operators and operands (variables and values) that represents a single result value. Expressions are evaluated to give that result.

Question 40

float

Answer 40

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 41

increment

Answer 41

Both as a noun and as a verb, increment means to increase by 1.

Question 42

initialization (of a variable)

Answer 42

To initialize a variable is to give it an initial value. Since in Python variables don’t exist until they are assigned values, they are initialized when they are created. In other programming languages this is not the case, and variables can be created without being initialized, in which case they have either default or garbage values.

Question 43

int

Answer 43

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

Question 44

integer division

Answer 44

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 45

keyword

Answer 45

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 46

modulus operator

Answer 46

Also called remainder operator or integer remainder operator. Gives the remainder after performing integer division.

Question 47

object

Answer 47

Also known as a data object (or data value). The fundamental things that programs are designed to manipulate (or that programmers ask to do things for them).

Question 48

operand

Answer 48

One of the values on which an operator operates.

Question 49

operator

Answer 49

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

Question 50

prompt string

Answer 50

Used during interactive input to provide the use with hints as to what type of value to enter.

Question 51

reference diagram

Answer 51

A picture showing a variable with an arrow pointing to the value (object) that the variable refers to. See also state snapshot.

Question 52

rules of precedence

Answer 52

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

Question 53

state snapshot

Answer 53

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 54

statement

Answer 54

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 55

str

Answer 55

A Python data type that holds a string of characters.

Question 56

type conversion function

Answer 56

A function that can convert a data value from one type to another.

Question 57

value

Answer 57

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

Question 58

variable

Answer 58

A name that refers to a value.

Question 59

variable name

Answer 59

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.