创建2个txt格式文件，user.txt和userlock.txt
注册的时候将用户名和密码写入user.txt
一行用户名，一行密码，
在登录时，进入user.txt按行查找用户名和密码，找到用户名后用flag标记为1，
下一行如果与密码匹配则跳出循环，不匹配清除flag重新输入密码，避免跳行查找密码
如果三次登录失败，则将此时的用户名添加到userlock.txt，下次登录的时候遍历userlock.txt
如果匹配跳出循环不再输入密码
file = open(r'E:\PythoneDATA\Firtday\user.txt','w+')
while True:
choose = int(input("choose to select "
"\n1.sign up"
"\n2.sign in"
"\n0.exit"
"\n"))
if choose==1:
_username = input("username:")
while True:
_password1=input("password:")
_password2=input("enter password again:")
if(_password1!=_password2):
print("your password isn't currect"
"please enter again")
else:
print("successfully sign up ")
break
with open(r'E:\PythoneDATA\Firtday\user.txt','w+') as file:
file.write(_username)
file.write('\n'+_password1+'\n')
file.close()
if choose==2:
file = open(r'E:\PythoneDATA\Firtday\user.txt', 'r')
print('''
------------------------------------------
Welcome,please enter your
username and password
------------------------------------------''')
sign_in=0
for i in range(3,0,-1):
username = input(' username:')
password = input(' passward:')
flag=0
for i, line in enumerate(file2):
if username== line:
print("this account has been locked")
break;
for i, line in enumerate(file):
if line==username:
flag+=1
continue
if flag==1 and line==password:
print('succeessfully sign in')
sign_in=1
break
if flag==1 and line!=password:
flag-=1
if flag<0:
print("username or password error")
sign_in=0
break
if sign_in==0:
print("you have {0} times to try".format(i))
if i>=3:
with open(r'E:\PythoneDATA\Firtday\userlock.txt', 'w+') as file2:
file2.write(username)
print("this account has been locked")
if choose==0:
break
