《python核心编程第二版》第二章练习答案解析

2-5循环和数字

a

i=1while i < 11:    print i    i+=1

b

for i in range(11):    print i

2-6条件判断

m = int(raw_input())if m < 0:    print 'negative'elif m == 0:    print '0'else :    print 'positive'

2.7循环和字串

str = raw_input()i = len(str)n = 0while n < i:    print str[n]    n +=1    for j in str:    print j    

2.8循环和操作符

num = 0for i in range(5):    num += int(raw_input())print num

2.9循环和操作符

num = 0for i in range(5):    num += int(raw_input())print float(num)/5

2.10带循环和条件判断的用户输入

flag = 1while flag:    n = float(raw_input('Enter a numbre between 1 and 100'))    if (n >= 1) & (n <= 100):        flag = 0

2.11

# -*- coding: utf-8 -*- list = [1,1,1,1,1]print '1.请输入五个数'print '2.求和'print '3.求平均'print '输入x退出'n = (raw_input('请输入'))while n is not 'x':    n = int(n)    if n == 1:        for i in range(5):            list[i] = float(raw_input())    elif n == 2:        num = 0        for j in list:            num += j        print num    elif n == 3:        num = 0        for j in list:            num += j        print float(num)/5.0    else:        print '输入错误'    n = (raw_input('请输入'))