print() vs return

In this lesson we will be examining the differences between using a print() statement and a return statement

Example Function: Average of Integers in a List

def averagePrint1(array):
    ''' averagePrint1() outputs the total average of all the integers in a list

    argument:
    -- array : a list of integers
    '''

    total_sum = sum(array)
    length = len(array)
    average = total_sum / length

    print('The average of the given list of values is:', average)
# end of averagePrint1

def averagePrint2(array):
    ''' averagePrint() returns the total average of all the integers in a list

    argument:
    -- array : a list of integers
    '''

    total_sum = sum(array)
    length = len(array)
    average = total_sum / length

    return average
# end of averagePrint2

# Start of the actual program

values = [96, 42, 55, 4, 12, 14, 67, 25, 37, 82, 62, 13]

print('Executing avereagePrint1():')
averagePrint1(values)
print('Executing avereagePrint2():')
averagePrint2(values)
print('-'*25)

print('Setting variables result1:')
result1 = averagePrint1(values)
print('Setting variables result2:')
result2 = averagePrint2(values)

print('-'*25)
print('Variable result1:', result1)
print('Variable result2:', result2)

Executing avereagePrint1():
The average of the given list of values is: 42.416666666666664
Executing avereagePrint2():
-------------------------
Setting variables result1:
The average of the given list of values is: 42.416666666666664
Setting variables result2:
-------------------------
Variable result1: None
Variable result2: 42.416666666666664

print() vs return in our example

1. Calling the function without variable assignment:

When we first called averagePrint1(values), it outputted the message with the result

When we first called averagePrint2(values), it did not output anything

• This is the difference of using print() and return: print() outputs a message to the console whereas return does not

2. Assigning variables with the result of a function call:

When we output the variable result1 the value is None.

When we output the variable result2 the value is the resulting average.

• This happens because the function: averagePrint1 does not return any value; therefore, variable result1 cannot be assigned with the result from said function

• The function, averagePrint2, returns the average variable; therefore, it can be used for variable assignment

NOTE: 9 out of 10 times your functions should and will return a value