sweigart chapter 3

Question 1

function

Answer 1

like a mini program within a program. it lets you group code that gets executed multiple times.

Question 2

def statement

Answer 2

defines the function.

Question 3

body of the function

Answer 3

the code that follows the def statement. it is executed when the code is called.

Question 4

deduplicating

Answer 4

means getting rid of duplicated or copy-and-pasted code. doing this makes your program shorter, easier to read, and easier to update. if you duplicate and ever decide to update, you have to change the code everywhere you copied it.

Question 5

arguments

Answer 5

the values that are passed when a function is called. they are shown between parentheses.

Question 6

parameters

Answer 6

variables that contain arguments. when a function is called with arguments, the arguments are stored in parameters. this stored value will be forgotten once the function returns.

Question 7

return value

Answer 7

the value that a function call evaluates down to.

Question 8

return statement

Answer 8

allows you to specify what the return value should be when creating a function using a def statement. it consists of (1) the return keyword and (2) the value or expression that the function should return.

Question 9

None value

Answer 9

represents the absence of a value. it is the only value of the NoneType data type. it must be typed with a capital N. Python adds return None to the end of any function definition with no return statement. it is similar to how while and for loops implicitly end with a continue statement.

Question 10

keyword arguments

Answer 10

identified by the keyword put before them in a function call. they are often used for optional parameters.

Question 11

end keyword argument

Answer 11

two outputted strings automatically appear on separate lines because the print() function automatically adds a newline character. the end keyword argument is used to change the newline character to a different string.

Question 12

sep keyword argument

Answer 12

when you pass multiple string values to print(), the function will automatically separate them with a single space. you could replace the default separating string by passing the sep keyword argument a different string.

Question 13

call stack

Answer 13

the current function to be executed is always on top of the stack. it is how Python remembers where to return the execution after each function call. Python remembers which line of code called the function so that the execution can return there when it encounters a return statement. if that original statement called other functions, the execution would return those function calls first before returning to the original function call.

Question 14

frame object

Answer 14

store the line number of the original function call so that Python can remember where to return. Python creates a frame object on the top of the stack if a function is called. when a function call returns, Python removes a frame object from the top of the stack and moves the execution to the line number stored in it. frame objects are always added and removed from the top of the stack and not from any other place.

Question 15

local variables

Answer 15

parameters and variables that are assigned in a call function. they exist in that function’s local scope. they are also stored in frame objects on the call stack.

Question 16

global variables

Answer 16

variables that are assigned outside all functions. they exist in the global scope. a variable cannot be both local and global.

Question 17

scope

Answer 17

can be thought of as a container for variables. when a scope is destroyed, all values stored in the scope’s variables are forgotten.

Question 18

global scope

Answer 18

there is only one and it is created when your program begins. when your program terminates, the global scope is destroyed and all its variables are forgotten.

Question 19

local scope

Answer 19

created whenever a function is called. any variables assigned in the function exist within the function’s local scope. when the function returns, the local scope is destroyed and the variables are forgotten.

Question 20

global statement

Answer 20

can be used to modify a global variable from within a function.

Question 21

try and except statements

Answer 21

the code that could potentially have an error is put in a try clause. the program execution moves to the start of a following except clause if an error happens. after running that code, the execution continues as normal. any errors that occur in function calls in a try block will also be caught.