Sample Final

1. Evaluate each expression. Indicate floats by including a decimal point (so to show 1 as a float, write “1.0”). If any cannot be evaluated, say why.
   1. 3 + 5.0
   2. 10 % 4 + 7 // 2
   3. abs(5 - 20 // 3) ** 4
   4. "If %d + %d = %2.2f, then %s" % (2, 2, 4, "bye")
   5. 4 // "3"
2. Convert the following into Python; you may assume the string and math modules are imported already:
   1. The volume vol of a sphere is 4πr³ divided by 3 (remember the result is a floating point number!)
   2. The value of the string variable str with all occurrences of the letter “e” replaced by the character “3”
   3. Subtract 159 from the product of 3 and 27, using integers
3. What does the following function do when given a list of numbers as the argument?

   def f(lst):
       a = i = 0
       n = len(lst)
       while i < n:
           if lst[i] <= 0:
               i += 1
               continue
           a += lst[i]
           i += 1
       return a / n
   

4. Rewrite the function in problem 4 so that it uses a “for” loop, not a “while” loop.
5. What does the following program do:

   d = dict()
   while True:
       try:
           line = input("EOF to stop> ")
       except EOFError:
           break
       for i in line:
           d[i] = d.get(i, 0) + 1
   u = d.keys()
   for i in sorted(u):
       print(i, d[i])
   

6. What does the following program do:

   def y(n):
       if n < 10:
           return str(n)
       else:
           d = str(n % 10)
       return y(n // 10) + d
   
   print(y(174))
   

ECS 10, Basic Concepts of Computing Winter Quarter 2012