Python入門 ファイル内の文字列を検索したいのですが？

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with open('filename.txt', 'r') as f:
  for line in f:
  if 'Python' in line:
    print(line)
  else:
    print('String Not Found!')

import re
search_pattern = 'Python'
with open('filename.txt', 'r') as f:
  for line in f:
  match = re.search(search_pattern, line)
    if match:
  print(match.group())

with open("filename.txt", "r") as f:
  lines = f.read()
  for i, line in enumerate(lines.splitlines()):
    if "Python" in line:
      print(i + 1, line)

with open("filename.txt", "r") as f:
  lines = f.readlines()
    for i, line in enumerate(lines):
      if "Welcome" in line:
      print(i + 1, line)