Computer Science 15-110, Spring 2011
Class Notes: Code Tracing Practice

1. # while loop
   def f():
       x = 10
       y = 100
       print "before loop:", x, ",", y
       while (x < y/2):
           x += 1
           y /= 2
           print "in loop:", x, ",", y
       print "after loop:", x, ",", y
   f()
   

2. # for loop
   def f():
       x = 1
       y = 2
       print "before loop:", x, ",", y
       for z in range(y,y+3):
           x += z
           y -= x
           print "in loop:", x, ",", y
       print "after loop:", x, ",", y
   f()
   

3. # loop and conditional
   def f():
       x = 1
       y = 2
       print "before loop:", x, ",", y
       for z in range(30):
           if (z%10 == x%10):
               y += 4
               print "in loop, in if:", [x,y,z]
           elif (z%10 == y):
               x *= 3
               print "in loop, in elif:", [x,y,z]
       print "after loop:", [x,y,z]
   f()
   

4. # nested loop
   def f():
       w = 1
       x = 2
       print "before loop:", w, ",", x
       for y in range(3):
           for z in range(-5, 5):
               if (y+z == x+w):
                   w += x
                   x += 1
                   print "in loop, in if:", [w,x,y,z]
           print "after inner loop:", [w,x,y,z]
       print "after outer loop:", [w,x,y,z]
   f()

5. # function calls
   def f(x, y):
       x = y/2
       y = x/2
       return x + y
   
   def g(y, x):
       return f(x, y)
   
   def h():
       x = 13
       y = 42
       print f(x,y)
       print g(x,y)
       print g(f(x,y), g(x,y))
   
   h()