python基本if while 语句

结果输出 1 2 3 4 5 6 8 9
count = 1
while count < 10:
    count = count + 1
    if count == 7:
        print('')
    else:
        print(count)

输出0-100内的偶数
n = 1
while n < 101:
    temp = n % 2               求余
    if temp == 0:              余数为0输出结果
        print(n)
    else:                      否则pass

        pass
    n = n + 1

求1-2+3-4+5-6----99
n = 1
s = 0
while n < 100:
     temp = n % 2         把余数赋值给temp
     if temp == 0:        
         s = s - n
     else:
         s = s + n
     n = n + 1
print(s)

三次登陆验证
count = 0
while count < 3:
    user = input('>>>')       用户交换
    pwd = input('>>>')
    if user == 'alex' and pwd == '123':          条件语句
        print("欢迎登陆")
        print("......")
        break
    else:
        print("用户名或者密码错误")
    count = count + 1