# 1. Is the following assignment statement valid or invalid?
# If it is invalid, why?
72 = amount


# 2. What will the following code display?
val = 99
print('The value is', 'val')


# 3. Look at the following assignment statements
value1 = 99
value2 = 45.9
value3 = 7.0
value4 = 7
value5 = 'abc'
value6 = value1 + value2
value7 = 'value1' + 'value2'
value8 = 14 / 5
value9 = 14 // 5
value10 = 14 % 5
value11 = 10 * 3
value12 = '10' * 3
value13 = 10 ** 3
value14 = '10' ** 3       # what is wrong?


# After these statement execute,
# what is the Python data type and values
# referenced by each variable?
print(type(value1), value1)
print(type(value2), value2)
print(type(value3), value3)
print(type(value4), value4)
print(type(value5), value5)
print(type(value6), value6)
print(type(value7), value7)
print(type(value8), value8)
print(type(value9), value9)
print(type(value10), value10)
print(type(value11), value11)
print(type(value12), value12)
print(type(value13), value13)
print(type(value14), value14)   # What is wrong?



# 4. What will be displayed by the following program?
my_value = 99
print(type(my_value), my_value)
my_value = 'my_value'
print(type(my_value), my_value)
my_value = 99.0
print(type(my_value), my_value)
print(int(my_value))
print(str(my_value))
print(float(str(my_value)))
print(int(str(my_value)))    # What is wrong?



# 5. What would the following code print?
def compare_things(a, z):
    if 'z' < 'a':
        print('z is less than a.')
    else:
        print('z is not less than a.')

compare_things(5, 3)


# 6. What would the following code print?
def compare_things2(a, z):
    if z < a:
        print(z, "is less than", a)
    else:
        print(z, "is not less than", a)

compare_things2(5, 3)


# 7. What would the following code print?
#    If there are errors, what are the errors?
#    How should the code be fixed?
def compare_things3(a, z):
    if z < a:
        print(z + " is less than " + a)
    else:
        print(z + " is not less than " + a)

compare_things3(5, 3)

# TypeError: unsupported operand type(s) for +: 'int' and 'str'
# To fix, cost a and z to string type
# def compare_things3(a, z):
#     if z < a:
#         print(str(z) + " is less than " + str(a))
#     else:
#         print(str(z) + " is not less than " + str(a))
#
# compare_things3(5, 3)


# 8. What would the following code print?
#    If there are errors, what are the errors?
#    How should the code be fixed?
def compare_things4(a, z):
    if z < a:
        print(z, "is less than", a)
    else:
        print(z, "is not less than", a)

compare_things4('5', '3')
print("a = " + a + " and z = " + z)    # What is wrong?

# a and z are local variables
# To fix, make them of global scope, use the "global" keyword
# def compare_things4():
#     global a
#     global z
#     if z < a:
#         print(z, "is less than", a)
#     else:
#         print(z, "is not less than", a)
#
# a = '5'
# z = '3'
# compare_things4()
# print("a = " + a + " and z = " + z)


# 9. What would the following code print?
def compare_things5():
    global a
    global z
    z = 13
    if z < a:
        print(z, "is less than", a)
    else:
        print(z, "is not less than", a)

a = 5
z = 3
compare_things5()
print("a = " + str(a) + " and z = " + str(z))


# 10. Write a function that return the size of a given word.
#     For example, if the word is 'hello', the function
#     should return 5
def get_length(word):
    return len(word)

print(get_length('hello'))


# 11. What does the following code print
a = False
if not a:
    print('not a')
else:
    print('otherwise')



### extra (not in exam 1) -- if you are curious ###
# good problem solving, function, and local and global practice
# but probably too much to ask for exam1
# 111x-S2019: we don't ask any recursive programming in exam 1
#             feel free to do it for fun
# 12. Write a function that return a factorial of a given number
def factorial(number):
    global result
    if number > 0:
        result = result * number
        number -= 1
        factorial(number)

    return result

result = 1     # why should result be initialized to 1
print(factorial(3))
result = 1     # reset it. why?
print(factorial(4))
result = 1
print(factorial(5))