如何从文本文件中提取特定文本

Question

Hello Stackoverflow community,

I have problem regarding my code that I am trying to retrieve some specific text from a text file, Which I am able to to do. But I am using the seek method to retrieve the data. But for that I am giving the starting position of the text and the end position of the text. Which gives me the exact output what I want. But some times the length of the retrieving text might be longer then my code doesn't retrieve the whole text. So how can I do that

I am using python2.7 and trying to retrieve the specific data from a text file

file = open("C:\Users\This_PC\p4.txt", "r")
file.seek(645)
string = file.read(13 - 0)
print string

I am getting the out put as expected like test_label123 . But when in the text file if the length of the text is longer like test_label12345 then I am getting the output as test_label123 which is wrong.

p4.txt content is mentioned below

# A Perforce Label Specification.
#
#  Label:       The label name.
#  Update:      The date this specification was last modified.
#  Access:      The date of the last 'labelsync' on this label.
#  Owner:       The user who created this label.
#  Description: A short description of the label (optional).
#  Options:     Label update options: [un]locked, [no]autoreload.
#  Revision:    Optional revision specification to make an automatic label.
#  ServerID:    If set, restricts access to the named server.
#  View:        Lines to select depot files for the label.
#
# Use 'p4 help label' to see more about label views.

Label:  test_label123

Owner:  This_PC

Description:
    Created by Auto12

Options:    unlocked noautoreload

Answer 1

You may use regular expressions , so something similar to this

import re

file = open("test.txt", "r")
string = file.read()
m = re.search('(?<=Label:) {0,2}(\w+)', string)

print m.group(1)

You may need to tweak your regexp to properly read the second apperance and not the first one ( Label: The label name. )