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