用户登陆--判断输入密码错误3次后冻结该账号

'''
先创建user、lock文件，user存储账号密码，用于登录时判断，lock文件为账号错误3次后，冻结
user内容格式为：
{'name':'zhangsan','passwd':'123'}
{'name':'lisi','passwd':'123'}
{'name':'wangwu','passwd':'123'}
'''

import os
'''此方法暂时未用到try/except'''

def lock(_name):
    '''判断一个用户是否冻结'''
    if os.path.getsize("lock"):
        with open("lock","r") as f:
            for line in f:
                if line.strip() == "":
                    continue
                line = eval(line)
                if line["name"] == _name and line["num"] == 3:
                    return 0
            else:
                return -1
    else:
        return -1

def clear_lock():
    '''当程序退出时，删除非冻结的账号信息'''
    list = []
    with open("lock","r+") as f:
        for line in f:
            if line.strip() == "":
                continue
            line = eval(line)
            if line["num"] == 3:
                list.append(line)
        f.truncate(0)
    with open("lock","w") as f1:
        for i in list:
            f1.write(str(i) + '\n')

def login(_name,_passwd):
    '''用户登陆'''
    with open("user","r") as f:
        flag = 0
        for line in f:
            if line.strip() == "":
                continue
            line = eval(line)
            if line["name"] == _name:
                if line["name"] == _name and line["passwd"] == _passwd:
                    return 0
                else:
                    return 1
        return -1

def write_lock(_name):
    '''将输入错误的账号写入lock文件'''
    #文件不为空
    if os.path.getsize("lock"):
        list = []
        with open("lock","r+") as f:
            flag = 0
            for line in f:
                if line.strip() == "":
                    continue
                line = eval(line)
                #判断账号是否存在
                if line["name"] == _name:
                    line["num"] += 1
                list.append(line)
            else:
                dict2 = {}
                dict2["name"] = _name
                dict2["num"] = 1
                list.append(dict2)
        with open("lock","w") as f1:
            for i in list:
                f1.write(str(i) + '\n')


    #空文件直接写入
    else:
        list1 = []
        dict1 = {}
        dict1["name"] = _name
        dict1["num"] = 1
        list1.append(str(dict1))
        with open("lock","w") as f2:
            for j in list1:
                f2.write(str(j) + '\n')

def main():
    name = input("用户名:")
    res = lock(name)
    if res == 0:
        print("%s已被冻结，请联系管理员"%name)
        clear_lock()
        exit()
    passwd = input("密码:")
    res1 = login(name,passwd)
    if res1 == 0:
        print("欢迎%s登陆51CTO"%name)
        clear_lock()
        exit()
    elif res1 == 1:
        print("密码错误")
        write_lock(name)
    else:
        print("账号不存在")

    res2 = lock(name)
    if res2 == 0:
        print("%s已被冻结，请联系管理员" %name)
        clear_lock()
        exit()

while True:
    main()