8.13. Exercises

1. Write code that asks the user to enter a numeric score (0-100). In response, it should print out the score and corresponding letter grade, according to the table below.

   Score	Grade
   >= 90	A
   [80-90)	B
   [70-80)	C
   [60-70)	D
   < 60	F

   The square and round brackets denote closed and open intervals. A closed interval includes the number, and open interval excludes it. So 79.99999 gets grade C , but 80 gets grade B.

   scores = [77.51, 92.86, 98.01, 69.71, 78.52, 59.69, 60.49, 85.04, 87.33, 91.04] ==== from unittest.gui import TestCaseGui import re import math class myTests(TestCaseGui): def testOne(self): output = self.getOutput().split('\n') editor = self.getEditorText().split('\n') float_re = r'[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?' _grades=[] for score in scores: _score = float(score) if _score >= 90: _grades.append('A') elif _score >= 80: _grades.append('B') elif _score >= 70: _grades.append('C') elif _score >= 60: _grades.append('D') else: _grades.append('F') self.assertEqual(grades, _grades) # hardcode check # LOOK FOR IF STATEMENTS outer_ifs = re.findall(r'^(if[ (].*: *)$', self.getEditorText(), re.M) outer_elifs = re.findall(r'^(elif[ (].*: *)$', self.getEditorText(), re.M) outer_elses = re.findall(r'^(else *: *)$', self.getEditorText(), re.M) inner_ifs = re.findall(r'^( +if[ (].*: *)$', self.getEditorText(), re.M) inner_elifs = re.findall(r'^( +elif[ (].*: *)$', self.getEditorText(), re.M) inner_elses = re.findall(r'^( +else *: *)$', self.getEditorText(), re.M) self.assertTrue(len(outer_ifs)==0 and len(outer_elifs)==0 and len(outer_elses)==0 and len(inner_ifs)==1 and len(inner_elifs)==3 and len(inner_elses)==1, 'Checking if-statements') # LOOK FOR for STATEMENTS outer_loops = re.findall(r'^(for[ (].* in.*: *)$', self.getEditorText(), re.M) inner_loops = re.findall(r'^( +for[ (].* in.*: *)$', self.getEditorText(), re.M) self.assertTrue(len(outer_loops)==1 and len(inner_loops)==0, 'Checking for-statements') myTests().main()

   sc = input("Enter a score from 0 to 100 (decimal points are allowed)") fl_sc = float(sc) if fl_sc < 60: gr = "F" elif fl_sc < 70: gr = "D" elif fl_sc < 80: gr = "C" elif fl_sc < 90: gr = "B" else: gr = "A" print("Score", fl_sc, "gets a grade of", gr)

2. A year is a leap year if it is divisible by 4; however, if the year can be evenly divided by 100, it is NOT a leap year, unless the year is also evenly divisible by 400 then it is a leap year. Write code that asks the user to input a year and output True if it’s a leap year, or False otherwise. Use if statements.

   Year	Leap?
   1944	True
   2011	False
   1986	False
   1800	False
   1900	False
   2000	True
   2056	True

   Above are some examples of what the output should be for various inputs.

   years = [1967, 1900, 1400, 1628, 1701, 1217, 1359, 1300, 2000, 1054, 1724, 1000, 1800, 1100, 2100, 1023, 1600, 1500, 1358, 1160, 1700, 1744, 2009, 1200] ==== from unittest.gui import TestCaseGui import re import math class myTests(TestCaseGui): def testOne(self): output = self.getOutput().split('\n') editor = self.getEditorText().split('\n') float_re = r'[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?' _is_leap_year = [] for _year in years: if _year % 4 == 0 : if _year % 100 == 0: _is_leap_year.append( _year % 400 == 0) else: _is_leap_year.append(True) else: _is_leap_year.append(False) self.assertEqual(is_leap_year, _is_leap_year, 'Checking answer') # hardcode check float_re = r'[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?' print_float_re = r'print\( *'+float_re+' *\)' self.assertFalse(re.search(print_float_re, self.getEditorText()), 'Checking for hardcoding') # LOOK FOR IF STATEMENTS outer_ifs = re.findall(r'^(if[ (].*: *)$', self.getEditorText(), re.M) outer_elifs = re.findall(r'^(elif[ (].*: *)$', self.getEditorText(), re.M) outer_elses = re.findall(r'^(else *: *)$', self.getEditorText(), re.M) inner_ifs = re.findall(r'^( +if[ (].*: *)$', self.getEditorText(), re.M) inner_elifs = re.findall(r'^( +elif[ (].*: *)$', self.getEditorText(), re.M) inner_elses = re.findall(r'^( +else *: *)$', self.getEditorText(), re.M) self.assertTrue(len(outer_ifs)==0 and len(outer_elifs)==0 and len(outer_elses)==0 and len(inner_ifs)>=1 and len(inner_elifs)>=0 and len(inner_elses)>=0, 'Checking if-statements') # LOOK FOR for STATEMENTS outer_loops = re.findall(r'^(for[ (].* in.*: *)$', self.getEditorText(), re.M) inner_loops = re.findall(r'^( +for[ (].* in.*: *)$', self.getEditorText(), re.M) self.assertTrue(len(outer_loops)==1 and len(inner_loops)==0, 'Checking for-statements') myTests().main()

3. What do these expressions evaluate to?

   1. 3 == 3

   2. 3 != 3

   3. 3 >= 4

   4. not (3 < 4)

   1. True

   2. False

   3. False

   4. False

4. Give the logical opposites of these conditions, meaning an expression that would produce False whenever this expression produces True, and vice versa. You are not allowed to use the not operator.

   1. a > b

   2. a >= b

   3. a >= 18  and  day == 3

   4. a >= 18  or  day != 3

5. Provided are the lengths of two sides of a right-angled triangle. Assign the length of the hypotenuse the the variable hypo_len. (Hint: x ** 0.5 will return the square root, or use sqrt from the math module)

   side1 = 3 side2 = 4 ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(hypo_len,5,"Testing that hypo_len has been set correctly") myTests().main()

6. Provided is a list of numbers. For each of the numbers in the list, determine whether they are even. If the number is even, add True to a new list called is_even. If the number is odd, then add False.

   num_lst = [3, 20, -1, 9, 10] ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(is_even, [False, True, False, False, True],"Testing that is_even is set correctly.") myTests().main()

7. Provided is a list of numbers. For each of the numbers in the list, determine whether they are odd. If the number is odd, add True to a new list called is_odd. If the number is even, then add False.

   num_lst = [3, 20, -1, 9, 10] ==== from unittest.gui import TestCaseGui import re class myTests(TestCaseGui): def testOne(self): self.assertEqual(is_odd, [True, False, True, True, False],"Testing that is_odd is set correctly.") # LOOK FOR IF STATEMENTS outer_ifs = re.findall(r'^(if[ (].*: *)$', self.getEditorText(), re.M) outer_elifs = re.findall(r'^(elif[ (].*: *)$', self.getEditorText(), re.M) outer_elses = re.findall(r'^(else *: *)$', self.getEditorText(), re.M) inner_ifs = re.findall(r'^( +if[ (].*: *)$', self.getEditorText(), re.M) inner_elifs = re.findall(r'^( +elif[ (].*: *)$', self.getEditorText(), re.M) inner_elses = re.findall(r'^( +else *: *)$', self.getEditorText(), re.M) self.assertTrue(len(outer_ifs)==0 and len(outer_elifs)==0 and len(outer_elses)==0 and len(inner_ifs)==1 and len(inner_elifs)==0 and len(inner_elses)==1, 'Checking if-statements') myTests().main()

8. Given the lengths of three sides of a triange, determine whether the triangle is right angled. If it is, the assign True to the variable is_rightangled. If it’s not, then assign False to the variable is_rightangled.

   Hint: floating point arithmetic is not always exactly accurate, so it is not safe to test floating point numbers for equality. If a good programmer wants to know whether x is equal or close enough to y, they would probably code it up as

   if  abs(x - y) < 0.001:      # if x is approximately equal to y
       ...
   

   a = 5 b = 6 c = 8 ==== from unittest.gui import TestCaseGui import re import math class myTests(TestCaseGui): def testOne(self): output = self.getOutput().split('\n') editor = self.getEditorText().split('\n') float_re = r'[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?' _is_rightangled = False if abs(a**2 + b**2 - c**2) < 1e-7: _is_rightangled = True elif abs(a**2 - b**2 + c**2) < 1e-7: _is_rightangled = True elif abs(-a**2 + b**2 + c**2) < 1e-7: _is_rightangled = True self.assertEqual(is_rightangled, _is_rightangled, 'Checking answer') # hardcode check float_re = r'[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?' print_float_re = r'print\( *'+float_re+' *\)' self.assertFalse(re.search(print_float_re, self.getEditorText()), 'Checking for hardcoding') # LOOK FOR IF STATEMENTS outer_ifs = re.findall(r'^(if[ (].*: *)$', self.getEditorText(), re.M) outer_elifs = re.findall(r'^(elif[ (].*: *)$', self.getEditorText(), re.M) outer_elses = re.findall(r'^(else *: *)$', self.getEditorText(), re.M) inner_ifs = re.findall(r'^( +if[ (].*: *)$', self.getEditorText(), re.M) inner_elifs = re.findall(r'^( +elif[ (].*: *)$', self.getEditorText(), re.M) inner_elses = re.findall(r'^( +else *: *)$', self.getEditorText(), re.M) self.assertTrue(len(outer_ifs)>=1 and len(outer_elifs)>=0 and len(outer_elses)>=0 and len(inner_ifs)>=0 and len(inner_elifs)>=0 and len(inner_elses)>=0, 'Checking if-statements') # LOOK FOR for STATEMENTS outer_loops = re.findall(r'^(for[ (].* in.*: *)$', self.getEditorText(), re.M) inner_loops = re.findall(r'^( +for[ (].* in.*: *)$', self.getEditorText(), re.M) self.assertTrue(len(outer_loops)>=0 and len(inner_loops)>=0, 'Checking for-statements') myTests().main()

9. Implement the calculator for the date of Easter.

   The following algorithm computes the date for Easter Sunday for any year between 1900 to 2099.

   Ask the user to enter a year. Compute the following:

   1. a = year % 19

   2. b = year % 4

   3. c = year % 7

   4. d = (19 * a + 24) % 30

   5. e = (2 * b + 4 * c + 6 * d + 5) % 7

   6. dateofeaster = 22 + d + e

   Special note: The algorithm can give a date in April. You will know that the date is in April if the calculation gives you an answer greater than 31. (You’ll need to adjust) Also, if the year is one of four special years (1954, 1981, 2049, or 2076) then subtract 7 from the date.

   Your program should print an error message if the user provides a date that is out of range.

   year = int(input("Please enter a year")) if year >= 1900 and year <= 2099: a = year % 19 b = year % 4 c = year % 7 d = (19*a + 24) % 30 e = (2*b + 4*c + 6*d + 5) % 7 dateofeaster = 22 + d + e if year == 1954 or year == 2981 or year == 2049 or year == 2076: dateofeaster = dateofeaster - 7 if dateofeaster > 31: print("April", dateofeaster - 31) else: print("March", dateofeaster) else: print("ERROR...year out of range")

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10. Get the user to enter some text and print out True if it’s a palindrome, False otherwise. (Hint: Start by reversing the input string, and then use the == operator to compare two values to see if they are the same)

11. Write a program that will print out a greeting to each student in the list. This list should also keep track of how many students have been greeted and note that each time a new student has been greeted. When only one student has entered, the program should say “The first student has entered!”. Afterwards, the program should say “There are {number here} students in the classroom!”.

            students = ["Jay", "Stacy", "Iman", "Trisha", "Ahmed", "Daniel", "Shadae", "Tosin", "Charlotte"]
    ====
    num_students = 0
    ====
    for student in students:
    ====
        print("Welcome to class, " + student)
        num_students += 1
    ====
        if num_students == 1:
            print("The first student has entered!")
    ====
        elif num_students > 1:
            print("There are " + str(num_students) + " students in the classroom!")
            

12. Piece together a program so that it can successfully print out one print statement, given the value of x.

            x = 16
    ====
    if x > 10:
    ====
        if x > 20:
            print("This is a large number!")
    ====
        else:
            print("This is a pretty big number.")
            

8.13.1. Contributed Exercises

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