核心编程答案（第二章）（自编）

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2-10

1.使用try...ecxept来判断输入的是否为数字

#!/usr/bin/env python# encoding: utf-8while 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-8import ipdbdef 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_avedef 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_sumwhile 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-8import ipdba = [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 - 1print a

2.这个参考的，比较符合

#!/usr/bin/env python# encoding: utf-8import ipdba = 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, aif b > c:    b, c = c, bprint a, b, c

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