Test 2 Review B: Questions

R2b.1.

Why does Python use modules, rather than simply building all desirable functions into the language?

R2b.2.

Write a program that computes and displays the value of the following expression. (All angles in radians.)

sin 1 + sin 2 + sin 3 + … + sin 10

R2b.3.

The following two code fragments are identical, except that Fragment A uses elif where B uses if. Give an example value for score where the fragments behave differently, and explain the difference in behavior.

Fragment A Fragment B
if score >= 90: print('A') elif score >= 70: print('C') else: print('F') if score >= 90: print('A') if score >= 70: print('C') else: print('F')

Fragment A	Fragment B
`if score >= 90: print('A') elif score >= 70: print('C') else: print('F')`	`if score >= 90: print('A') if score >= 70: print('C') else: print('F')`

R2b.4.

Assume year is an integer representing a year between 2001 and 2399. Below, complete the if statement so that it tests whether year represents a leap year. (Recall that leap years occur when the year is a multiple of 4 but not of 100. You don't need to worry about multiples of 400.)

if

    print(str(year) + ' is a leap year.')

R2b.5.

Complete the below if statement so that the body executes when the square of x isn't between 99 and 101.

if : x = (x + 1.0 / x) / 2.0

R2b.6.

Suppose we have a vertical line segment from (lx,ly0) to (lx,ly1) (where ly0 < ly1). What should go into an if statement's condition to test whether a point (px,py) lies on that line?

if                            :

  print('point on line')

R2b.7.

What is the output of the following program?

word = 'quintessential'

line = ''

for i in range(len(word)):

    for c in word[:i]:

        if c == word[i]:

            line = line + c

            break

print(line)

R2b.8.

Translate the following program to an equivalent program that doesn't use a break statement.

word = input()

c = '(none)'

for i in range(1, len(word)):

    if w[i] == w[i - 1]:

        c = w[i]

        break

print(c)

Test 2 Review B: Solutions

R2b.1.

Building all desirable functions into the language would introduce a huge number of names that one would want to avoid when choosing a variable name, since choosing a variable of the same name would mean that the function of the same name would be inaccessible.

Alternative answer: Modules provide a mechanism for people to build libraries of additional functionality beyond what's built in Python, for others to use in their own Python programs.

R2b.2.

import math

total = 0

for x in range(1, 11):

    total = total + math.sin(x)

print(total)

R2b.3.

If score is 92, then Fragment A will display just “A”, while Fragment B will display “A” and “C” on separate lines.

(The two fragments behave identically when score is below 90.)

R2b.4.

if year % 4 == 0 and year % 100 != 0:

    print(str(year) + ' is a leap year.')

R2b.5.

if x * x < 99 or x * x > 101

R2b.6.

px == lx and py >= ly0 and py <= ly1

R2b.7.

senti

R2b.8.

word = input()

i = 1

while i < len(word) and w[i] != w[i - 1]:

    i += 1

if i == len(word):

    print('(none)')

else:

    print(w[i])