## Comp 150 Exam 1 Study Guide

Exam 1 is Wednesday, Feb 20, 2019

### Sections of Python:

There will be a couple simple python functions to write on the exam. You
will also be asked to describe the OUTPUT of some simple python
functions.

answers will be coming soon.

You will receive this Python summary
on the exam.

1. What is printed by the following?

x=3

y=5

print('{} * {} = {}'.format(x,y,x*y))

print('+'*x + "hello" + '+'*y)

2. What is the value of the number s after execution of the following python
code:

n=1

s=1

while n<7:

s = s + n*n

n = n+2

3. What is the value of L after execution of the following python
code? Note L is a list.

n = 0

L = []

while n < 5:

L = L + [2*n]
# same as L.append(2*n)

n = n + 1

4. What are the values of x and y at the end of the following loop:

x=1

y=0

while y < 20:

y = y+x

x = x+1

Hint: make a table of x,y values as of the start of the loop. Initially
(x,y) = (1,0); after one time through (x,y) = (2,1)

5. What is printed by the following?

for i in range(1,5):

print(i)

6. What is printed by the following? There is one pair of numbers per
line.

for i in range(1,5):

for j in
range(0,i):

print(i,j)

7. What is string t after the following? Note that the last line adds each
letter of s in turn to the **end** of t:

t = ""

s = "foobar"

for i in range(len(s)):

t = t + s[i]

8. Write a python function to multiply all the numbers in a list L:

def mulnums(L):

mulnums([2,3,7]) should return 42.

9. Suppose we define

def
filter(L):
# L is a list of numbers

res = [ ]
# an empty list

for x in L:

if x % 2 == 1: res = res +
[x] # the condition here is
true if x is odd

return res
# res = res+[x] is the same as res.append(x)

What is returned by filter([1, 2, 4, 5, 7, 12, 16, 17])?

10. Below is a while loop. Convert it to a for loop, with an appropriate
range().

i=1

sum=0

while i < 6:

sum += i

i += 1