python 核心编程课后练习(chapter 2)

2-4

1 #2-4(a)

2 print "enter a string"

3 

4 inputstring = raw_input()

5 

6 print"the string is: ", inputstring

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1 #2-4(b)

2 print "enter a number:"

3 

4 num = raw_input()

5 

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

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2-5

 

#2-5(a)

i = 0

while i<=10:

  print i

  i+=1

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1 # 2-5(b)

2 for i in range(11)

3   print i

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2-6

 1 #2-6

 2 print "please input a number:"

 3 

 4 num = raw_input()

 5 

 6 if int(num) < 0:

 7   print" a negative number!!!"

 8 elif int(num) > 0:

 9   print "a positive number!!!"

10 else:

11   print "zero"

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2-7

1 #2-7

2 print "please input a string:"

3 

4 inputstring = raw_input()

5 

6 while 

7 

8 for e in inputstring:

9   print e

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2-8

 1 #2-8

 2 print "please input a string:"

 3 

 4 inputstring = raw_input()

 5 i = 0

 6 while i<len(inputstring):

 7   print inputstring[i],

 8   i+=1

 9 print  

10 for e in inputstring:

11   print e

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2-9

 1 #2-9

 2 arrary = [1, 2, 3, 4, 4]

 3 

 4 sum = 0

 5 for e in arrary:

 6   sum += e

 7 

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

 9 

10 print ev

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2-10

 1 #2-10

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

 3 

 4 num = int(raw_input())

 5 

 6 while num<1 or num >100:

 7   print "please input again:"

 8   num = int(raw_input())

 9 

10 print "num is valid

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2-11

 1 #2-11

 2 # to support cn

 3 #encoding: utf-8

 4 print """(1)取五個數的和"""

 5 print "(2)取五個數的平均值..."

 6 print "(x)退出"

 7 def sum(arrary):

 8   s = 0

 9   for e in arrary:

10     s += e

11   return s  

12 

13 def average(arrary):

14   if len(arrary) == 0:

15     return 0

16   else:  

17     return float(sum(arrary))/float(len(arrary))

18 

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

20 

21 while True:

22  opt = raw_input()

23  if opt == 'x':

24    print "退出"

25    break

26  elif int(opt) == 1:

27    print "the sum of the arrary is :", sum(arr)  

28  elif int(opt) == 2:

29    print "the average of the arrary is:", average(arr)

30  else:

31    print "please input again" 

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2-14

 1 #2-14

 2 #sort

 3 

 4 print "enter three number:"

 5 

 6 print "the first is:"

 7 a = raw_input()

 8 print "the second is:"

 9 b = raw_input()

10 print "the third is:"

11 c = raw_input()

12 

13 print "after sort for low to high:"

14 

15 if a > b:

16    tmp = a

17    a = b

18    b = tmp

19 if a > c:

20    tmp = a

21    a = c

22    c = tmp

23    

24 if b > c:

25   tmp = b

26   b = c

27   c = tmp

28 

29 print a, b, c  

30 

31  

32 print "after sort for high to low:"

33 

34 if a < b:

35    tmp = a

36    a = b

37    b = tmp

38 if a < c:

39    tmp = a

40    a = c

41    c = tmp

42    

43 if b < c:

44   tmp = b

45   b = c

46   c = tmp

47 

48 print a, b, c  

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