webinar-functions-2020-05-15.py

# Webinar: Functions + Methods

# DEFINE it once
# CALL it as many times as needed

# Know the difference PARAMETER and ARGUMENT
# the value for a parameter variable is given by a particular argument on a specific call

# function definition, Gallant
def squareThis(num):
     return num * num # we don't need to give the parameter a value, just use it

# RETURN means the function call itself evaluates to the value returned. This makes the function very useful!
# PRINT() just shows us output so we can see it right now.

# On the Pre + OA, do whichever the questions asks you to do.
# I like to say "Return by default, unless the question specifically asks you to print."

# call the function
squareThis(5) # arg of 5, should get a result of 25
print(squareThis(5)) # print() the call so I can see it
print(squareThis(6)) # arg of 6, should get us 36

# don't be Goofus
def squareSomething(num):
    num = 5 # don't do this! the calls provide values
    print(num * num) # this will always be 25!

print(squareThis(10)) # Gallant will be right, with 100
print(squareSomething(10)) # Goofus hopes you like 25


x = squareThis(3) # because the function RETURNS a value, it can be used in assignment...
print(x)
y = squareThis(4) + 5 # ... and as part of more complex expressions
print(y)

# Ch 8 Task 1
#Task 1:
#Complete the function to print the first X number of characters in the given string
def printFirst(mystring, x):
    # x = 3 # don't do this!
    print(mystring[0:x])


printFirst('WGU College of IT', 3)   # expected output: WGU
printFirst('WGU College of IT', 11)  # expected output: WGU College

# The class METHODS you'll be learning over the later chapters are themselves FUNCTIONS. They're functions that "belong" to that type of object
myList = [2, 4, 7, 5, 9]
print(dir(list)) # see the methods of the list class
help(list.sort) # see help on this specific method
myList.sort() # The list class sort() method orders the list. This method doesn't return a value, but other list methods do.
print(myList)