Python 在文件中搜索确切的字符串

Question

import re

def find_string(file_name, word):
   with open(file_name, 'r') as a:
       for line in a:
           line = line.rstrip()
           if re.search("^{}$".format(word),line):
             return True
   return False

if find_string('/tmp/myfile', 'hello'):
    print("found")
else:
    print("not found")

myfile:

hello world #does not match
hello #match

If I remove ^ and $ then it will match but it will also match "he","hel" etc. How can I match the exact string if there are multiples words on a single line?

Answer 1

You may try using word-boundaries around your text. Something like:

\bhello\b

You can find the demo of the above regex in here.

Sample implementation in Python

import re
def find_string(file_name, word):
   with open(file_name, 'r') as a:
       for line in a:
           line = line.rstrip()
           if re.search(r"\b{}\b".format(word),line):
             return True
   return False

if find_string('myfile.txt', 'hello'):
    print("found")
else:
    print("not found")

You can find the sample run of the above implementation in here.

Answer 2

Do you want something like this? Sorry if not

import re

with open('regex.txt', 'r') as a:
    word = "hello"
    for line in a:
        line = line.rstrip()
        if re.search(r"({})".format(word), line):
            print(f'{line} ->>>> match!')
        else:
            print(f'{line} ->>>> not match!')

text file:
hello world #does not match
hello #match
test here
teste hello here

[output]
hello world #does not match ->>>> match!
hello #match ->>>> match!
test here ->>>> not match!
teste hello here ->>>> match!