python核心编程（第二章习题）

2-3、在python中取余与C中不同。在python中

>>> 9 % 4.0

1.0

而在C中取余操作只能对一个int型的进行取余。2 + “str”这样会报错，与C中一样。

2-5#!/usr/bin/env python

#Filename: test.py

i = 0

while (i <= 10):

    print i

i += 1

对于for循环来说，range（N），取的数是0到N-1

#!/usr/bin/env python

#Filename: test.py

for i in range(11):

    print i

2-11s =  raw_input(),从键盘输入得到的是一个字符串，如果你输入5，相当于‘5’，如果你要把它当成数据的数，要把它进行转换：int(s)

#!/usr/bin/env python

#Filename: test.py

while True:

    sum = 0

    for i in range(5):

        str = raw_input("please input num:")

        sum += int(str)

    while True:   

        print "Please select:"

        print "(1)sum of five number"

        print "(2)average of five number"

        print "(x)quit"

        s = raw_input()

        if (s == 'x'):

            exit()

        elif (s == '1'):

            print "the sum is %d" %(sum)

            break

        elif (s == '2'):

            print "the average is %d" % (sum / 5.0)

            break

        else:

            print "Error,Please select again!"