所以基本上我有一个程序可以在文档中创建用户用户名和密码，并搜索与使用该程序的人输入的用户名一起使用的密码。
例如： 程序要求我输入我输入的用户名：'13'。 文本文档中的13下是'sadfsdfsdf'。 我希望程序跳到'Username：13'以下，然后阅读并打印'Password：sadfsdfsdf'。
请注意，我在.txt文件中有多个用户名和密码
u ='用户名：'
提前致谢！
def SearchRecordProgram():
while True:
user_search = input("Please enter the username you wish to see the password for: ")
full_user = u + user_search
if full_user in open('User_Details.txt').read():
print(" ")
print ("Username found in our records")
print(" ")
print(full_user)
break
else:
print("Username entered does not match our records")
答案 0 :(得分：1)
所以，想象你的文件是这样的：
Username : 13
Password : sadfsdfsdf
Username : 15
Password : Lalalala
您可以解析它（使用正则表达式），如下所示：
import re # regular expression module
regex = re.compile("Username :(.*)\nPassword :(.*)")
# read text from file
with open(filePath,'r') as f:
text = f.read()
u_pass = regex.findall(text)
# [(' 13', ' sadfsdfsdf'), (' 15', ' Lalalala')]
user_dict = {u:password for u,password in u_pass}
# {' 13': ' sadfsdfsdf', ' 15': ' Lalalala'}
现在，您可以通过询问该用户的密码来获取某人的密码：
# given username and password_input
if username in user_dict and user_dict[username] == password_input:
# if username exists and password okay
print "Authentication succeeded."
答案 1 :(得分：0)
也许不是美女，但这样的事情会奏效：
with open(users_file, "r") as f:
lines = f.read()
def get_password(user_id):
entries = iter(lines.splitlines())
for entry in entries:
if(entry.startswith("{}:{}".format(prefix, user_id))):
return next(entries)
print "Password:", get_password("13")
答案 2 :(得分：0)
def SearchRecordProgram():
while True:
user_search = input("Please enter the username > ")
file = open('User_Details.txt')
usernames = file.readlines() # Read file into list
file.close()
if user_search in usernames: # Username exists
print ('Found Username')
password = usernames[usernames.index(user_search)+1]
print ('Password is: ' + password)
break # Exit loop
else: # Username doesn't exist
print("Username entered does not match our records")
请注意，如果密码恰好是用户名，则无法使用，例如：
user1
password1
user2
user3 # This is the password for user3
user3
password3
如果您搜索“user3”，此代码将输出“user3”作为“user3”的密码，因为它找到“user3”的第一个实例（第4行），然后查看下一行（第5行），这是下一个用户名。
更糟糕的是，如果“user3”是文件中的最后一行，它将以错误结束，因为没有更多行。您可以使用以下代码添加检查找到的用户名的索引是否为偶数（即索引0,2,4,8）：
if not usernames.index(user_search) % 2: # Checks the remainder after / by 2.
# If it's 0 then it's an even index.
password = usernames[usernames.index(user_search)+1]
print ('Password is: ' + password)
但如果发生这种情况，你就无能为力。
但是，您可以将用户名文件操作为仅具有以下用户名：
lst = [0, 1, 2, 3, 4, 5, 6, 7]
print (lst[0::2])
打印
[0, 2, 4, 6]
所以代码可以改为：
def SearchRecordProgram():
while True:
user_search = input("Please enter the username > ")
usernames = open('User_Details.txt').readlines() # Read file into list
if user_search in usernames[0::2]: # Username exists
print ('Found Username')
password = usernames[1::2][usernames[0::2]].index(user_search)]
print ('Password is: ' + password)
break # Exit loop
else: # Username doesn't exist
print("Username entered does not match our records")
这是一个细分
password = usernames[1::2] # Gets the odd items (passwords)
[ # Get index item. The index returned from searching
# the usernames will be the same as the index needed
# for the password, as looking at just the odd items:
# [0, 2, 4, 6]
# [1, 3, 5, 7] - even has the same index as next odd.
usernames[0::2] # Gets even items (usernames)
].index(user_search)]
# Only searches the usernames. This
# means passwords being the same is not
# an issue - it doesn't search them
答案 3 :(得分：0)
如果要打开文件，几乎应该始终使用with语句：
with open('User_Details.txt') as read_file:
# Do reading etc. with `read_file` variable
这将确保正确处理任何错误并且文件未保持打开状态。
现在该文件已打开，我们需要遍历每一行，直到找到与我们的用户名匹配的行。我希望你知道for loop是如何运作的：
username = 'Username: 13' # Get this however you want
with open('User_Details.txt') as read_file:
for line in read_file:
line = line.strip() # Removes any unnecessary whitespace characters
if line == username:
# We found the user! Next line is password
我们需要获取包含密码的下一行。有很多方法可以获得下一行，但一种简单的方法是使用next()函数，它只是从迭代中获取下一个元素（在这种情况下是文件的下一行）：
username = 'Username: 13'
with open('User_Details.txt') as read_file:
for line in read_file:
line = line.strip()
if line == username:
password = next(read_file)
break # Ends the for loop, no need to go through more lines
现在您有了密码和用户名，您可以随心所欲地使用它们。将输入和输出置于程序逻辑之外通常是一个好主意，所以不要在for循环内打印密码，而是在那里接收密码然后在外面打印。
您甚至可能希望将整个搜索逻辑转换为函数：
def find_next_line(file_handle, line):
"""Finds the next line from a file."""
for l in file_handle:
l = l.strip()
if l == line:
return next(file_handle)
def main():
username = input("Please enter the username you wish to see the password for: ")
username = 'Username: ' + username
with open('User_Details.txt') as read_file:
password = find_next_line(read_file, username)
password = password[len('Password: '):]
print("Password '{0}' found for username '{1}'".format(password, username))
if __name__ == '__main__':
main()
最后，以这种格式存储任何是绝对疯狂的（更不用说密码安全的东西了，但我让你只是学习东西），为什么不做点什么像：
username:password
markus:MarkusIsHappy123
BOB:BOB'S PASSWORD
然后可以很容易地将其转换为词典：
with open('User_Details.txt') as read_file:
user_details = dict(line.strip().split(':') for line in read_file)
现在要获取用户名的密码，您可以：
username = input('Username: ')
if username in user_details:
print('Password:', user_details[username])
else:
print('Unknown user')