第一次迭代后Python脚本中断

Question

I am trying to do the following in python. Read xml file with usernames, pw, email addresses and so on. I then want to iterate through the passwords and try to find them in a different file. if there is a match, print the username and password. this is what i have so far:

import xml.etree.ElementTree as ET

tag = "multiRef"


tree = ET.parse('user.xml')
pwlist = open('swapped.txt', 'r')

for dataset in tree.iter(tag):
    password = dataset.find("password")
    pw = password.text
    user = dataset.find("username").text
    if pw in pwlist.read():
        print user
        print pw

Unfortunately, the script only prints one result and ends with no error or anything. I know, that there have to be at least 250 results... Why is it stopping after one result? Absolute python newb, a detailed explanation would be much appreciated!

Answer 1

if pw in pwlist.read() shouldn't be inside the loop. The first time through the loop, read() will return the entire file. The second time through it will return nothing because you are at END OF FILE.

Read the contents into a list prior to the loop and then refer to the list inside the loop.

Also consider the pattern with open(...) as f to make sure you are closing the file, since I don't see an explicit close().

with open('swapped.txt', 'r') as f:
   pw_list = f.readlines()

for ...

Answer 2

The error is that you are calling read on each iteration. After one read you must call .seek(0) to reset the pointer. That, however is a not the best solution for this, so you may want to try something like this:

import xml.etree.ElementTree as ET

tag = "multiRef"


tree = ET.parse('user.xml')
with open('swapped.txt', 'r') as fin:
    pwlist = fin.read()

for dataset in tree.iter(tag):
    password = dataset.find("password")
    pw = password.text
    user = dataset.find("username").text
    if pw in pwlist:
        print user
        print pw

This way you only read the file once and close it afterward (by using a context manager ). You can find more information on working with files in Python here .