Does Python change my string??

The related question is I was using a little shellcode in my python but failed
PS: I was doubting what’s is the end charecter of Python String or C string, if the string have the end charecter, how to deal with it? Does this related to this question?
Actually,
\x49isI.A word of explanation about this:
\x49means “Char with code 49 in hex. 49 in hex isint('49', 16):73.73is the ASCII character code forI, which you can verify with:ord('I'):73.