[英]How to erase specific data in file python
I cant seem to write each line in a file so Its like a one long string like : "a,1;b,2;c,3". 我似乎无法在文件中写入每一行,因此它就像一个长字符串,例如:“ a,1; b,2; c,3”。 I want to write a method that deletes "b,2" for example.
我想编写一个例如删除“ b,2”的方法。 Also, I cant write it with lines and that why im a bit confused and stuck... Thnks for all the helpers.
另外,我不能用线条写它,这就是为什么我有点困惑和卡住...所有助手的想法。
class Data:
def __init__(self):
print "are you ready?? :)"
def add_data(self, user_name, password):
add = open("user_data.txt", "a")
add.write(user_name + "," + password + ";")
add.close()
def show_file(self):
file = open("user_data.txt", "r")
print file.read()
file.close()
def erase_all(self):
file = open("user_data.txt", "w")
file.write("")
file.close()
def return_names(self):
file = open("user_data.txt", "r")
users_data = file.read()
users_data = users_data.split(";")
names = []
for data in users_data:
data = data.split(",")
names.append(data[0])
file.close()
return names
def is_signed(self, user_name):
names = self.return_names()
for name in names:
if user_name == name:
return True
return False
def is_password(self, user_name, password):
file = open("user_data.txt", "r")
users_data = file.read()
users_data = users_data.split(";")
for data in users_data:
data = data.split(",")
if data[0] == user_name:
if data[1] == password:
return True
file.close()
return False
def erase_user(self, user_name):
pass
As mentioned in the comments, you'll want to include newlines each time you write a line to the file. 如评论中所述,每次向文件中写入一行时,您都希望包含换行符。 Just a suggestion, to make file handling easier you may want to consider using with open() each time you access the file.
只是一个建议,为了使文件处理更容易,您可能需要在每次访问文件时考虑将其与open()一起使用。
So altogether, for example for the first class methods: 因此,例如,一类方法:
def add_data(self, user_name, password):
with open('user_data.txt', 'a') as add:
add.write(user_name + ',' + password + ';')
add.write('\n') # <-- this is the important new line to include
def show_file(self):
with open('user_data.txt') as show:
print show.readlines()
... and similar for other methods. ...和其他方法类似。
As for the method that deletes a user entry from the file: 至于从文件中删除用户条目的方法:
# taken from https://stackoverflow.com/a/4710090/1248974
def erase_user(self, un, pw):
with open('user_data.txt', 'r') as f:
lines = f.readlines()
with open('user_data.txt', 'w') as f:
for line in lines:
user_name, password = line.split(',')[0], line.split(',')[1].strip('\n').strip(';')
if un != user_name and pw != password:
f.write(','.join([user_name, password]))
f.write(';\n')
test: 测试:
d = Data()
d.erase_all()
d.add_data('a','1')
d.add_data('b','2')
d.add_data('c','3')
d.show_file()
d.erase_user('b','2')
print 'erasing a user...'
d.show_file()
output: 输出:
are you ready?? :)
['a,1;\n', 'b,2;\n', 'c,3;\n']
erasing a user...
['a,1;\n', 'c,3;\n']
confirm line entry was removed from textfile: 确认行条目已从文本文件中删除:
a,1;
c,3;
Hope this helps. 希望这可以帮助。
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