使用Python在txt文件中查找字符串

Question

I have a .txt file that is rather large--roughly 70K lines.

I'm trying to use Python to find all the instances of the string "Cannot update".

When I open the file and use ctrl-f on "Cannot update" it instantly finds it; however, when using RegEx in Python, .find(), or if in, it simply cannot find the string. Please see three methods I have used below:

RegEx method:

f = open('C:\PerfupD.txt', 'r')

strings = re.findall('Cannot update', f.read())

print(strings)

.find():

with open('C:\PerfUpD.txt', 'r') as file:

    for line in file:

          if line.find('Cannot update') != -1:

              print("Errors found")

if in:

with open('C:\PerfUpD.txt', 'r') as file:

    for line in file:

          if 'Cannot update' in line:

              print("Errors found")

I even tried searching for "Ca" and it can't find anything, but when I just search "C" it finds tons of instances...One side note is that this .txt file is generated from a website that initially saves the file as a .err file. I then save it as .txt.

The only thing I can think of is that perhaps the data in the file is generated in some other form but looks like regular text when open. Any insight is much appreciated!

Answer 1

you could probably just do this:

f = open('your file.txt', 'r+')
for line in f:
    if 'Cannot Update' in line:
        print('error found')

no need for regex