Checkpoints

#6.1
(1) Reuse code; (2) Reduce complexity; (3) Easy to maintain

#6.2
You can define a function using def keyword followed by function name
ex: def myFuction(param1):
    ...statements...

To inovke a function, just write it's name in the proper line

#6.3
def max(n1,n2):
    return n1 if n1>n2 else n2

#6.4
A call to a None function is always a statement itself(TRUE), but a call to a
value-returning function is always a component of an expression(FALSE).

#6.5
Yes,we can have a return statement in in a None function.
No,no syntax errors.

#6.6
The header begins with the def keyword, followed
by the function’s name and parameters, and ends with a colon.
The variables in the function header are known as formal parameters or simply parameters.
A parameter is like a placeholder: When a function is invoked, you pass a value to the parameter.
This value is referred to as an actual parameter or argument.

#6.7
(1) def computeSalesCommisions(salesAmount,salesRate):. Should return a value.
(2) def printCalendar(month,year):. No return is needed.
(3) def squarRoot(num):. Either print the result or return return it.
(4) def isEven(n):. should return a value.
(5) def computeMonthlyPayment(loanAmount,years,annualInterestRate):. Either print the result or return return it.
(6) def upper(c):. No return is needed.

#6.8
8.	Line 2, 5-10: not indented correctly.

#6.9
None.

#6.10
The program prints None, as min function does not return a value.

#6.11
In positional arguments, the arguments are passed in the same order as
their respective parameters in the function header.
In keyword arguments, passing each argument in the form name=value.

#6.12
f(1, p2 = 3, p3 = 4, p4 = 4): correct
f(1, p2 = 3, 4, p4 = 4): wrong
f(p1 = 1, p2 = 3, 4, p4 = 4): wrong
f(p1 = 1, p2 = 3, p3 = 4, p4 = 4): correct
f(p4 = 1, p2 = 3, p3 = 4, p1 = 4): correct

#6.13
A variable for an object is actually a reference to the object.
When you invoke a function with arguments, the reference value of each argument is
passed to the parameter. This is referred to as pass-by-value in programming terminology

#6.14
Yes.

#6.15
(a) 0
(b)

2
2 4
2 4 8
2 4 8 16
2 4 8 16 32

(c)
Before the call, variable times is 3
n =  3
Welcome to CS!
n =  2
Welcome to CS!
n =  1
Welcome to CS!
After the call, variable times is 3

(d)


i is 1
 1
i is 2
 2 1
i is 3
then an infinite loop

i is 1
 1
i is 2
 2 1
i is 3

#6.16
-Before invoking max, the stack contains the space required for the main function
with max variable = 0.
-In the max function, the first element in the stack is the space required for max function
with variables max = 0, value 1 =1 and value2 = 2. The next element in the stack is the
space required for main function with max variable = 0.
-Before max return statement, the elements are the same except that max = 2 in the space of max function.
-Return back to main function, the stack contains only space required for main function with max = 0.

#6.17
(a)
2
3.4
2
4
(b)
3
6
5

#6.18
The variables x and y which are used in lines 8 and 9 are not
defined outside the function.

#6.19
Yes. It prints y is 1

#6.20
1 2
5 2
1 24
4 5

#6.21
The parameter n (has non-default argument) should be defined before parameter message(has a default argument).

#6.22
The later definition replaces the previous definitions.

#6.23
Yes.
14 4 45 1.8

#6.24
random.randint(34, 55)

#6.25
chr(random.randint(ord('B'),ord('M')))

#6.26
6.5 + random.random() *49.9

#6.27
chr(random.randint(ord('a'),ord('z')))