Python efficient way to check if very large string contains a substring

Question

Python is not my best language, and so I\'m not all that good at finding the most efficient solutions to some of my problems. I have a very large string (coming from a 30 MB

Answer 1

Are you implying that only a complete line will match? (your EDIT: matching on a newline only example seems to)

Then I imagine

for line in open('file').readlines():
  if line==small_string:
    return True
return False

IE, using == is quicker than 'in' - perhaps. I wouldn't be surprised if the underlying implementation of in catches the case where the line to search and the string to search for are the same length and just attempts an == itself.

woudl be better.