python要开始记录了20181125

print('1、使用while循环输入 1 2 3 4 5 6     8 9 10')
i = 1
while i < 10:
    i += 1
    if i == 7:
         continue       #print(' ')这两个可以替换一下，看看不同的效果
    else:
        print(i)


print('2、求1-100的所有数的和')
i = 0
sum = 0
while i < 100:
      i += 1
      sum = sum + i
      print(sum)

      
print('3、输出 1-100 内的所有奇数')
i = 0
while i < 100:
    i += 1
    if i %2 != 0:
        print(i)
        

print('4、输出 1-100 内的所有偶数')
i = 0
while i < 100:
    i += 1
    if i %2 == 0:
        print(i)

print('5、求1-2+3-4+5 ... 99的所有数的和')
i = 0
sum = 0
j = -1
while i < 99:
    i += 1
    if i %2 != 0:
        sum = sum + (i * (-j))
    if i %2 == 0:
        sum = sum + (i * j)
print(sum)

print('6、用户登陆（三次机会重试）')
i = 0
name = 'allison'
password = '123456'
while i < 3:
    na = input('请输入用户名：')
    pw = input('请输入密码：')
    i += 1
    oppo = 3 - i
    if na == name and pw == password:
        print('输入正确')
        break
    elif na != name or pw != password:
        print('输入错误， 还有%d次机会'%(oppo))
        if i == 3:
            answer = input('输入Y再试试？')
            if answer == 'Y':
                print('再来三次机会')
                i = 0 
            else:
                print('机会已用完')