Python-而循环在不应该结束时结束

Question

Python新手在这里。我正在编写一个简单的客户端/服务器程序，要求用户输入姓名、用户名、电子邮件地址、密码。此信息被发送到服务器，服务器将检查此用户的文本文件中是否已经有条目。如果有，它应该发送一条消息回来说这个用户已经存在，要求用户再试一次。

我设置了一个名为标志的变量为False。我对照文本文件检查用户信息，如果在文件中没有找到匹配，我将标志设置为true。然后我有一个if语句，它说如果标志是True，则将用户信息写入文件。

但是，当我输入重复信息时，它会发回相应的“user ready exists”消息，但仍会将重复信息写入UserProfile.txt文件。我一直在以不同的方式重新编写循环和if语句，看看它是否会带来不同，但不管怎样，我遇到了同样的问题。

from socket import *
from datetime import datetime
#Create a welcome socket bound at serverPort
serverPort = 12009
serverSocket = socket(AF_INET,SOCK_STREAM)
serverSocket.bind(('',serverPort))
serverSocket.listen(10)
print ('The Hello Name server is ready to receive')
accessTime = datetime.now();
print("Access time is", accessTime);
flag = False

while 1:

    while not flag:
        connectionSocket, addr = serverSocket.accept()
        #Wait for the hello message 
        sentence1 = connectionSocket.recv(1024)
        print("From", addr,sentence1.decode('ascii'))
        #Ask for name if a hello message is received
        if(sentence1.decode('ascii').upper() == "HELLO"):
            returnMessage1 = "Please provide the requested information."
        connectionSocket.send(returnMessage1.encode()) 
        #Wait for the name
        sentence2 = connectionSocket.recv(1024)
        fullName = sentence2.decode('ascii')
        #Wait for the email
        sentence3 = connectionSocket.recv(1024)
        email = sentence3.decode('ascii')
        #Wait for the username
        sentence4 = connectionSocket.recv(1024)
        userName = sentence4.decode('ascii')
        #Wait for the password
        sentence5 = connectionSocket.recv(1024)
        password = sentence5.decode('ascii')



        for line in open("UserProfile.txt").readlines():
            if line.find(userName) > -1:    #found the username in this record
                returnMessage3 = "Username already exists, please try again" #reject username
                connectionSocket.send(returnMessage3.encode())
            if line.find(fullName) > -1 and line.find(email) > -1:
                returnMessage4 = "Account already exists for this person, please try again" #reject email                 
            else:
                flag = True

    if flag:            

        #Prepare the access record with information separated by tab key
        userAccount = userName+"\t"+password+"\t"+fullName+"\t"+email+"\n"
        #Append the access record into accessRecord.txt
        output_file = open("UserProfile.txt", "a")
        output_file.write(userAccount)
        output_file.close()
        #Respond the client with the access information
        returnMessage2 = "Registration Successful"
        connectionSocket.send(returnMessage2.encode())

    connectionSocket.close()                #Close the connection

Answer 1

当您发现用户名已经存在时，您会发回回复，但不会停止。

尝试在if块中放置突破：

for line
    if user name in line
        send message about already exists
        break - out of for loop