Midterm Review

Terms and Ideas

Understand and be able to reasonably define the following terms:

algorithm
computer
program
machine code
assembly
high-level language
interpreter
integrated development environment (IDE)
shell
variable
type
string
int
float

Variables and I/O

What do the following programs print?


# assume the user enters 6
num = int(input("Enter a number: "))
total = num * 10
print(total)


# assume the user enters 'Dogs'
message = input("Enter a message: "))
print(message[3])


x = 7
y = x + 1
y = y * 2
z = x + y
print(z)


a = 3
b = 4
c = a + 2 * (b + 5)
print(c)

What is wrong with the following programs?


cost = input("Enter the cost: ")
tax = 0.053 * cost
print("Tax is" tax)


input("Enter your name: ")
print("Hello", name)


length = int(input("Enter length: "))
width = int(input("Enter width: ")
length * width = area
print(area)


age = 2019 - born
born = float(input("Enter year you were born: "))
print("You are about", age, "years old.")

Writing code

Write a program to convert from feet to meters. There are 3.28084 feet in one meter. First read in the number of feet, do the calculation to find how many meters that is, and then print the result.
Write a program to read in the radius of a circle from the user and print out the area. The area of a circle can be computed as $A = \pi \cdot R^2$
Write a program to print the average of 4 numbers that the user gives. You should read in the 4 numbers, compute the average, and then print the answer.

Conditionals

What do the following programs print?


name = input("What's your name? ")

if len(name) < 5:
    print("My you have a short name")
    print(name, "is a good name though!")
print("Thanks for running the program", name)

When the user enters "Bob"?
When the user enters "Montgomery"?


x = 7
y = 2

if y != 2:
    print("Apple")
elif x == 7:
    print("Banana")
else:
    print("Pear")


temp = 72

if temp < 20:
    print("Super cold")
elif temp < 60:
    print("Cold")
elif temp < 80:
    print("Nice")
elif temp < 90:
    print("Warm")
else:
    print("Hot")


temp = 72

if temp < 20:
    print("Super cold")
if temp < 60:
    print("Cold")
if temp < 80:
    print("Nice")
if temp < 90:
    print("Warm")
else:
    print("Hot")


age = int(input("How old are you? "))
height = int(input("How tall are you? "))

if age > 10 and height > 48:
    print("You can ride the roller coaster")
else:
    print("Sorry you can't ride")

If the user enters:

34 and 72
9 and 40
12 and 48
8 and 50


# this is the same program, except the and is an or
age = int(input("How old are you? "))
height = int(input("How tall are you? "))

if age > 10 or height > 48:
    print("You can ride the roller coaster")
else:
    print("Sorry you can't ride")

If the user enters:

34 and 72
9 and 40
12 and 48
8 and 50

Writing programs

The program above checks if the user meets the height and age requirement of a roller coaster. If they can ride it tells them so. If they can't it tells them they can't ride, but not why. Write a version of it that tells them either they can ride, they are not old enough, or they are not tall enough.

You are helping organize a large event which people need to check into. To help make checking in faster, you are dividing people by last name. Those with a last name beginning with a letter A–F check in at line 1. Those with a first letter from G–L go to line 2. Those with M–R go to line 3, and those with a first letter from S–Z go to line 4. Write a program which will ask the user for their last name and tell them which line to go to.

At UMW, students graduating in even years are said to be "Goats". Students graduating in odd years are said to be "Devils". Write a program to ask the user what year they are graduating, and tells them if they are a Devil or a Goat.

It's harder than you probably think to determine if a year is a leap year or not — it's not just every 4 years. The rules are:

If the year is divisible by 400 it's a leap year
Else if it's divisible by 100 it's not a leap year
Else if it's divisible by 4 it is a leap year
Otherwise it's not a leap year

Write a Python program to read in a year and tell the user whether it's a leap year or no.

Loops

What do the following programs print?


# assume the user enters the numbers "7 3 2 -1"
value = float(input("Enter a number: "))
prod = 1
while value > 0:
    prod = prod * value
    value = float(input("Enter a number: "))
print(prod)


number = 7
times = 0

while number > 0:
    number = number - 2
    times = times + 1
print(times)


# assume the user enters 5
start = int(input("Enter start: "))
for num in range(start, 0, -1):
    print(num, "...")
print("Blastoff!")


# assume the user enters 5
end = int(input("Enter end: "))

tot = 0
for i in range(1, val + 1):
    tot = tot + i
print(tot)

Writing Programs

Write a program that reads in a number from the user, and a message. The program should then print the message out "number" many times. For example, if they enter 3 and "Hello", then the program should print "Hello" three times.

Write a program which will let the user print the length of strings, for as many as they want. It should ask them to enter a string and then print the length of it. It should keep doing this until they enter an empty string (with a length of 0). Then the program should end.