python 入门到实践第五章课后练习

users = ['admin','alex','eric','crystol','joji']#创建一个列表

for i in users:#遍历整个列表
    if i.lower() == 'admin':#如果i的变量转换为小写后与‘admin’比对
        print("ni hao guanli yuan ")
    else:
        print("hello " + i + " see you agange!")

print("
")
'''5-9'''
del users[:]#删除列表中的全部元素

if users:
    for i in users:
        if i.lower() == 'admin':
            print("ni hao guanli yuan ")
        else:
            print("hello " + i + " see you agange!")
else:
    print("we need to find some users")
print("
")

'''5-10'''

curren_users = ['admin','alex','eric','crystol','joji']
new_users = ['admin','bobo','pigen','top','ALEX']

for i in new_users:
    if i.lower() in curren_users:
        print("你输入的用户名已被占用")
    else:
        print("用户名可以被使用")

print("
")

'''5-11'''
nums = list(range(1,10))

for i in nums:
    if i == 1:
        print(str(i)+"st")#整数+字符串时候提示错误，应该加上str() 转换
    elif i == 2:
        print(str(i)+"nd")
    elif i == 3:
        print(str(i)+"rd")
    else:
        print(str(i)+"th")