sweigart chapter 1

Question 1

interactive shell/Read-Evaluate-Print Loop (REPL)

Answer 1

lets you run (or execute) Python instructions one at a time and instantly shows you the results.

Question 2

expressions

Answer 2

consist of values (eg. 2) and operators (eg. +) and can always evaluate (reduce) down to a single value. a single value is also considered an expression but it evaluates only to itself. you can use expressions anywhere in Python code where you could also use a value.

Question 3

precedence

Answer 3

the order of operations. python math operators are similar to mathematics. parentheses can be used.

Question 4

data type

Answer 4

a category for values, where every value belongs to one data type.

Question 5

strings

Answer 5

text values surrounded by single quote (‘) characters, also known as strs.

Question 5

integer

Answer 5

eg. 1

Question 6

floating-point number (floats)

Answer 6

incorporates a decimal point, eg. 1.0

Question 7

empty/blank structure

Answer 7

a string with no characters in it (“).

Question 8

string concatenation operator

Answer 8

when + is used on 2 string values it joins the strings.

Question 9

string replication operator

Answer 9

when * is used on one string value and one integer value. it evaluates the expression down to a single string value that repeats the original string a number of times equal to the integer value.

Question 10

variable

Answer 10

a box in the computer’s memory where you can store a single value. if you want to use the result of an evaluated expression later in your program.

Question 11

assignment statement

Answer 11

used to store values in variables. it consists of a variable name, an equal sign (assignment operator), and the value to be stored.

Question 12

initialised

Answer 12

when the variable is created the first time a value is stored in it. after that, you can use it in expressions with other variables and values.

Question 13

overwriting a variable

Answer 13

when a variable is assigned a new value and the old value is forgotten.

Question 14

camelcase

Answer 14

using capitalised letter for every new word instead of underscores. eg. current_balance becomes currentBalance.

Question 15

file editor

Answer 15

used to write entire programs. in the file editor, instructions will not be run when you press enter. instead, you can save a file with many instructions and then run the program. it also does not have the&raquo_space;> prompt. you can start the program in the file editor so that it will start running in the interactive shell.

Question 16

terminates

Answer 16

when there are no more lines of code to execute, the Python program stops running.

Question 17

commenting out

Answer 17

every line following a hash mark (#) is called a comment and will be ignored by Python. it can be used as a note to yourself or to temporarily remove a line of code while testing a program.

Question 18

print() function

Answer 18

indicates that Python has to print out the text in a string.

Question 19

calling

Answer 19

executing a line with a function

Question 20

passed

Answer 20

when a line is executed and a function is called, the string value is passed to the function.

Question 21

argument

Answer 21

a value that is passed to a function call.

Question 22

len() function

Answer 22

evaluates to the integer value of the number of characters in a string value.

Question 23

input() function

Answer 23

waits for the user to send some text. this function evaluates to a string equal to the user’s text.

Question 24

int() function

Answer 24

can be helpful if you have a number as a string value that you want to use in mathematics. floating-point numbers will always be evaluated downwards.