python 核心编程课后练习(chapter 2)

2-4

 #2-4(a)
 print "enter a string"

 inputstring = raw_input()

 print"the string is: ", inputstring

 #2-4(b)
 print "enter a number:"

 num = raw_input()

 print "the number is: ", int(num)

2-5

#2-5(a)
i = 0
while i<=10:
  print i
  i+=1

 # 2-5(b)
 for i in range(11)
   print i

2-6

 #2-6
 print "please input a number:"

 num = raw_input()

 if int(num) < 0:
   print" a negative number!!!"
 elif int(num) > 0:
   print "a positive number!!!"
 else:
   print "zero"

2-7

 #2-7
 print "please input a string:"

 inputstring = raw_input()

 while 

 for e in inputstring:
   print e

2-8

 #2-8
 print "please input a string:"

 inputstring = raw_input()
 i = 0
 while i<len(inputstring):
   print inputstring[i],
   i+=1
 print
 for e in inputstring:
   print e

2-9

 #2-9
 arrary = [1, 2, 3, 4, 4]

 sum = 0
 for e in arrary:
   sum += e

 ev = float(sum)/float(len(arrary))

 print ev

2-10

 #2-10
 print "please input a number between 1-100"

 num = int(raw_input())

 while num<1 or num >100:
   print "please input again:"
   num = int(raw_input())

 print "num is valid

2-11

 #2-11
 # to support cn
 #encoding: utf-8
 print """(1)取五個數的和"""
 print "(2)取五個數的平均值..."
 print "(x)退出"
 def sum(arrary):
   s = 0
   for e in arrary:
     s += e
   return s  

 def average(arrary):
   if len(arrary) == 0:
     return 0
   else:
     return float(sum(arrary))/float(len(arrary))

 arr = [0, 1, 2, 3, 3]

 while True:
  opt = raw_input()
  if opt == 'x':
    print "退出"
    break
  elif int(opt) == 1:
    print "the sum of the arrary is :", sum(arr)
  elif int(opt) == 2:
    print "the average of the arrary is:", average(arr)
  else:
    print "please input again" 

2-14

 #2-14
 #sort

 print "enter three number:"

 print "the first is:"
 a = raw_input()
 print "the second is:"
 b = raw_input()
 print "the third is:"
 c = raw_input()

 print "after sort for low to high:"

 if a > b:
    tmp = a
    a = b
    b = tmp
 if a > c:
    tmp = a
    a = c
    c = tmp

 if b > c:
   tmp = b
   b = c
   c = tmp

 print a, b, c  

 print "after sort for high to low:"

 if a < b:
    tmp = a
    a = b
    b = tmp
 if a < c:
    tmp = a
    a = c
    c = tmp

 if b < c:
   tmp = b
   b = c
   c = tmp

 print a, b, c