Python Functions

Question 1

Function

Answer 1

A named sequence of statements that performs a computation.

Question 2

Function call

Answer 2

Evoking a function by its name.

*This is like a detour in the flow of execution. Instead of going to the next statement, the flow jumps to the body of the function, runs the statements there, and then returns to where it left off.

Question 3

Argument

Answer 3

The expression in parentheses after the name of a function.

*A function ‘takes’ an argument and ‘returns’ a result.

Question 4

Return value

Answer 4

The returned result of a function.

Question 5

When int() is used to convert floating-point values into integers, does it round off or omit the fraction?

Answer 5

int() omits the fraction of a floating-point value when converting it to an integer.

Question 6

Module

Answer 6

A file that contains a collection of related functions.

Question 7

Import statement

Answer 7

A statement used to import a module in order to use the functions therein.

*These statements create ‘module objects’

Question 8

How do you access one of the functions defined in a module object?

Answer 8

Specify the name of the module and the name of the function, separated by a dot (dot notation)

math. pi
math. sin()
math. log10()
math. sqrt()

Question 9

Function definition

Answer 9

Specifies the name of a new function and the sequence of statements that run when the function is called.

def NewFunction():
     print("I'm a good boy")

*Function definitions do not alter the flow of a program.

Question 10

def

Answer 10

The keyword that indicates that this is a function definition.

• The first character in the name of a function cannot be a number, and the name cannot be a keyword.
• A function does not have to take any arguments.

Question 11

Header

Answer 11

The first line of a function definition. It must end with a colon.

Question 12

Body

Answer 12

The rest of a function definition following the header. The body must be indented.

Question 13

Function object

Answer 13

Created when defining a function, it has type “function”.

Question 14

Can you use a function inside another function?

Answer 14

Yes, if it has already been defined.

Question 15

Statements inside a function are only run when the function is called. T/F?

Answer 15

True

Question 16

Flow of execution

Answer 16

The order in which the statements run in.

• Execution always begins at the first statement in a program, run one at a time, from top to bottom.
• Function definitions do not alter the flow of a program.

Question 17

When reading a program, do you read from top to bottom, or follow the flow of execution?

Answer 17

Read a program following the flow of execution.

Question 18

Parameter

Answer 18

The name assigned to an argument passed to a function

def name(bruce):
    print(bruce)

• This function assigns the argument to a parameter named ‘bruce’. When the function is called, it prints the value of the parameter. This works with any value that can be printed.
• Any kind of expression can be used as a parameter:

def print(2 * 4 + math.cos(math.pi))

• What we pass as an argument has nothing to do with the name of the parameter found in the function call.
• Each parameter corresponds to the same value as its corresponding argument

Question 19

When is the argument evaluated in a function?

Answer 19

The argument is evaluated before a function is called, and only once.

Question 20

Variables can be used as arguments, T/F?

Answer 20

True.

Question 21

Local

Answer 21

A variable only exists inside the function that it is created in. When the function terminates, the local variables are destroyed.

*Parameters are also local.

Question 22

Stack diagram

Answer 22

Show the value of each variable, and the functions they belong to. This keeps track of where variables can be used.

Each function is represented by a frame, with the name of the function beside it and the parameters and variables of the function inside it.

Question 23

main

Answer 23

Special name given to the topmost layer of a program. Anything declared globally will belong to main.

Question 24

Traceback

Answer 24

List of functions that tells you what program file the error occurred in, what line, and what functions were executing at the time. It also shows the line of code that caused the error. The order is the same as a stack diagram, and the function currently running is at the bottom.