Coursera Python 3 Programming Specialization - Course 2 - Week 3 - Function Basics - 12.5. Returning a value from a function

Function_Basics.py

#  Let’s start by creating a very simple mathematical function that we will call square. 
# The square function will take one number as a parameter and return the result of squaring that number. 
# Here is the black-box diagram with the Python code following.

def square(x):
    y = x * x
    return y

toSquare = 10
result = square(toSquare)
print("The result of {} squared is {}.".format(toSquare, result))



# First, an English plan for this new function to define called longer_than_five:
# *You’ll want to pass in a list of strings (representing people’s first names) to the function.
# *You’ll want to iterate over all the items in the list, each of the strings.
# *As soon as you get to one name that is longer than five letters, 
#  you know the function should return True – yes, there is at least one name longer than five letters!
# *And if you go through the whole list and there was no name longer than five letters, 
#  then the function should return False.

def longer_than_five(list_of_names):
    for name in list_of_names: # iterate over the list to look at each name
        if len(name) > 5: # as soon as you see a name longer than 5 letters,
            return True # then return True!
            # If Python executes that return statement, the function is over and the rest of the code will not run -- you already have your answer!
    return False # You will only get to this line if you
    # iterated over the whole list and did not get a name where
    # the if expression evaluated to True, so at this point, it's correct to return False!

# Here are a couple sample calls to the function with different lists of names. Try running this code in Codelens a few times and make sure you understand exactly what is happening.

list1 = ["Sam","Tera","Sal","Amita"]
list2 = ["Rey","Ayo","Lauren","Natalie"]

print(longer_than_five(list1))
print(longer_than_five(list2)



# What is wrong with the following function definition:

def addEm(x, y, z):
    return x+y+z
    print('the answer is', x+y+z)

# Ansuer : 
#B. You should not have any statements in a function after the return statement. 
#   Once the function gets to the return statement it will immediately stop executing the function.



# What will the following function return?

def addEm(x, y, z):
    print(x+y+z)

# Answer:
# A. The value None



# What will the following code output?

def square(x):
    y = x * x
    return y

print(square(5) + square(5))

# Answuer:
# B. 50



# What will the following code output?

def square(x):
    y = x * x
    return y

print(square(square(2)))

# Answuer:
# B. 16 ( It squares 2, yielding the value 4. 4 is then passed as a value to square again, yeilding 16.)



# What will the following code output?

def cyu2(s1, s2):
    x = len(s1)
    y = len(s2)
    return x-y

z = cyu2("Yes", "no")
if z > 0:
    print("First one was longer")
else:
    print("Second one was at least as long")

# Answer:
# C. First one was longer (cyu2 returns the value 1, which is assigned to z.)



# Which will print out first, square, g, or a number?

def square(x):
    print("square")
    return x*x

def g(y):
    print("g")
    return y + 3

print(square(g(2)))

# Ansuer:
# B. g (g has to be executed and return a value in order to know what paramater value to provide to x.)



# How many lines will the following code print?

def show_me_numbers(list_of_ints):
    print(10)
    print("Next we'll accumulate the sum")
    accum = 0
    for num in list_of_ints:
        accum = accum + num
    return accum
    print("All done with accumulation!")

show_me_numbers([4,2,3])

# Answer:
# B. 2 (Yes! Two printed lines, and then the function body execution reaches a return statement.)



# Write a function named same that takes a string as input, and simply returns that string.

# Answer:
def same(string):
    return string



# Write a function called same_thing that returns the parameter, unchanged.

# Answer:

def same_thing(x):
    return x



# Write a function called subtract_three that takes an integer or any number as input, 
# and returns that number minus three.

# Ansuer:

def subtract_three(x):
    return x - 3




# Write a function called change that takes one number as its input and returns that number, plus 7.

# Answer:

def change(x):
    return x + 7




# Write a function named intro that takes a string as input. Given the string “Becky” as input, 
# the function should return: “Hello, my name is Becky and I love SI 106.”

# Answer:

def intro(string):
    return("Hello, my name is " + string + " and I love SI 106.")

intro("Becky")
print(intro("Becky"))




# Write a function called s_change that takes one string as input and returns that string, 
# concatenated with the string ” for fun.”.

# Answer: 

def s_change(string):
    return(string + " for fun.")

s_change("I printed this")
print(s_change("I printed this"))



# Write a function called decision that takes a string as input, and then checks the number of characters. 
# If it has over 17 characters, return “This is a long string”, if it is shorter or has 17 characters, 
# return “This is a short string”.

# Answer:

def decision(string):
    if len(string) > 17:
        return ("This is a long string")
    return ("This is a short string")