练习1

求1-100的和
n = 1
s = 0
while n < 101:
    s = s + n
    n = n + 1
print(s)

使用while循环输入123456 8910
n = 1
while n < 11:
    if n ==7:
        pass
    else:
        print(n)
    n = n + 1
print('---end---')

　　

输出1-100内所有的偶数
n = 1
while n < 101:
    temp = n % 2
    if temp == 0:
        print(n)
    else:
        pass
    n = n + 1
print('---end---')

#求1-2+3-4+5···+99
n = 1
s = 0
while n < 100:
    temp = n % 2
    if temp == 0:
        s = s - n 
    else:
        s = s + n
    n = n + 1
print(s)

　　

输出1-100内所有的奇数

n = 1
while n < 101:
    temp = n % 2
    if temp == 0:
        pass
    else:
        print(n)
    n = n + 1
print('---end---')

　　

#用户登录（三次机会重试）
count = 0
while count < 3:
    user = input('>>>')
    pwd = input('>>>')
    if user == 'alex' and pwd == '123':
        print('欢迎登陆')
        break
    else:
        print('用户名或密码错误')
    count = count + 1