核心编程答案（第二章）（自编）

2-10

1.使用try...ecxept来判断输入的是否为数字

#!/usr/bin/env python
# encoding: utf-8

while 1:
try:
a = float(raw_input('plz input a number:'))
if 1 <= a <=100:
print 'success!'
break
else:
print 'plz input a number between 1~100!'
except ValueError:
print 'What you input is not a numer!'

2-11

1.用if语句来进行判断选择

#!/usr/bin/env python
# encoding: utf-8
import ipdb

def to_average():
the_sum = 0
a = 0
for i in range(0, 5):
a = float(raw_input('plz input the %dst number:' % (i + 1)))
the_sum = the_sum + a
the_ave = the_sum / 5.0
print the_ave

def to_sum():
the_sum = 0
a = 0
for i in range(0, 5):
a = float(raw_input('plz input the %dst number:' % (i + 1)))
the_sum = the_sum + a
print the_sum

while 1:
a = raw_input('plz choose want you want and input the number("1:average, 2:sum, 3:exit"):')
if a == '1':
to_average()
break
elif a == '2':
to_sum()
break
elif a == '3':
break
else:
print 'plz input the number'

2-15

1.貌似不太符合题目要求

#!/usr/bin/env python
# encoding: utf-8
import ipdb
a = [331, 32, 3]
for i in range(1, 3):
while(a[i] > a[i - 1]):
x = a[i - 1]
a[i - 1] = a[i]
a[i] = x
if i == 0:
continue
i = i - 1
print a

2.这个参考的，比较符合

#!/usr/bin/env python
# encoding: utf-8
import ipdb
a = int(raw_input('a='))
b = int(raw_input('b='))
c = int(raw_input('c='))
if a > b:
a, b = b, a  # 相互换值，两两对比，大于就换，小于等于就不动。
if a > c:
a, c = c, a
if b > c:
b, c = c, b
print a, b, c