"""File:     bin_srch0.py
   Purpose:  Implement binary search of a list of positive ints

   Run:      python bin_srch0.py

   Input:    A sorted list of positive ints
             Values to search for (<= 0 to quit)
   Output:   The location of the value in the list or None
             if the searched value isn't in the list.
   Note:     This version has a serious bug.
"""

def bin_srch(l, min, max, val):
   """See if val belongs to l between subscript min and subscript max"""
   mid = (min+max)/2
   if val == l[mid]:
      return mid
   elif val < l[mid]:
      return bin_srch(l, min, mid-1, val)
   else: # val > l[mid]
      return bin_srch(l, mid+1, max, val)

#----------------------------------------------------------------------
def read_ints(l):
   """Read a line of ints into the list l"""
   s = raw_input("Enter a sorted sequence of positive ints on one line\n")
   ls = s.split()
   for i in ls:
      l.append(int(i))


#----------------------------------------------------------------------
# Main program
l = []
read_ints(l)

val = int(raw_input("Enter a value to search for (<= 0 to quit)\n"))
while val > 0:
   loc = bin_srch(l, 0, len(l)-1, val)
   if loc != None:
      print "Found", val, "in subscript", loc
   else:
      print val, "isn't in the list"
   val = int(raw_input("Enter a value to search for (<= 0 to quit)\n"))

print "Bye!"