python要开始记录了20181125

 1 print('1、使用while循环输入 1 2 3 4 5 6     8 9 10')
 2 i = 1
 3 while i < 10:
 4     i += 1
 5     if i == 7:
 6          continue       #print(' ')这两个可以替换一下，看看不同的效果
 7     else:
 8         print(i)
 9 
10 
11 print('2、求1-100的所有数的和')
12 i = 0
13 sum = 0
14 while i < 100:
15       i += 1
16       sum = sum + i
17       print(sum)
18 
19       
20 print('3、输出 1-100 内的所有奇数')
21 i = 0
22 while i < 100:
23     i += 1
24     if i %2 != 0:
25         print(i)
26         
27 
28 print('4、输出 1-100 内的所有偶数')
29 i = 0
30 while i < 100:
31     i += 1
32     if i %2 == 0:
33         print(i)
34 
35 print('5、求1-2+3-4+5 ... 99的所有数的和')
36 i = 0
37 sum = 0
38 j = -1
39 while i < 99:
40     i += 1
41     if i %2 != 0:
42         sum = sum + (i * (-j))
43     if i %2 == 0:
44         sum = sum + (i * j)
45 print(sum)
46 
47 
48 
49 
50

 1 print('6、用户登陆（三次机会重试）')
 2 i = 0
 3 name = 'allison'
 4 password = '123456'
 5 while i < 3:
 6     na = input('请输入用户名：')
 7     pw = input('请输入密码：')
 8     i += 1
 9     oppo = 3 - i
10     if na == name and pw == password:
11         print('输入正确')
12         break
13     elif na != name or pw != password:
14         print('输入错误， 还有%d次机会'%(oppo))
15         if i == 3:
16             answer = input('输入Y再试试？')
17             if answer == 'Y':
18                 print('再来三次机会')
19                 i = 0 
20             else:
21                 print('机会已用完')