Lecture 13 - Exercises

13A - Strings and Tuples are Sequences

1. Consider the following function:

   def pr(a):
       for c in a:
           print(c, c, end=" ")

   The result of calling this function with a particular string a is C C S S C C E E Y Y E E. What was a?

2. What does the following program print?

   def fl(tu):
        r = ""
        for v in tu:
            r += str(v + v)
        return r
   print(fl(("A", "C", 3)))

13B - Indexing and Slicing

3. Suppose s = "Winter is cold." Which of the following evaluates to "r"?

   1. s[5]
   2. s(5)
   3. s[6]
   4. s(6)

4. Suppose last_name = "Wehrwein". Which of the following evaluates to "in"? List all that apply.

   1. last_name[7:8]
   2. last_name[-2:8]
   3. last_name[6:-1]
   4. last_name[-3:]
   5. last_name[6:]

5. Which of the following evaluates to the last character of a string s?

   1. s[len(s) - 1]
   2. s[len(s)]
   3. s[len(s) + 1]
   4. s[42]

6. Suppose last_name = "wehrwein". For which of the following a and b will last_name[a] == last_name[b] evaluate to True? List all that apply.

   1. a = 1, b = 5
   2. a = 1, b = 7
   3. a = 8, b = -4
   4. a = -2, b = -6

7. What does the following code print?

   m = (4, 1, 2, 2, 2)
   s = "Scott"
   for i in range(len(s)):
       print(s[i] * m[i], end="")

8. Consider the following function:

   def flop(value, number):
       output = ""
       for i in range(number, 0, -1):
           output = output + value[i-1]
   
       for i in range(number, len(value)):
           output = output + value[i]
       return output

   Suppose a contains an integer. Which of the following are possible return values of the following call:

   flop("no time", a)

   List all that apply:

   1. mit one
   2. nomite
   3. t onime
   4. on time
   5. emit on
   6. timeno time