使用Python 2.7.10解码ASCII字符串

Question

I'm fairly new to Python so I'm probably still making a lot of rookie mistakes.

I was comparing two seemingly matching strings in Python, but it always returned false. When I checked the representation of the object, I found that one of the strings was encoded in ASCII.

The representation of the first string returns:

'\x00"\x00i\x00t\x00i\x00n\x00e\x00r\x00a\x00r\x00y\x00_\x00o\x00p\x00t\x00i\x00o\x00n\x00s\x00_\x00s\x00e\x00a\x00r\x00c\x00h\x00_\x00b\x00u\x00t\x00t\x00o\x00n\x00"\x00 \x00=\x00 \x00"\x00L\x00a\x00u\x00n\x00c\x00h\x00 \x00t\x00h\x00e\x00 \x00s\x00e\x00a\x00r\x00c\x00h\x00"\x00;\x00'

While the representation of the second string returns:

"itinerary_options_search_button" = "Launch the search";

I'm trying to figure out how to decode the first string to get the second string, so that my comparison of the two will match. When I decode the first string with

string.decode('ascii')

I get a unicode object. I'm not sure what to do to get the decoded string.

Answer 1

Your first string seems to have some issues. I'm not entirely sure why there is so many null characters ( \\x00 ), but either way, we could write a function to clean those up:

s_1 = '\x00"\x00i\x00t\x00i\x00n\x00e\x00r\x00a\x00r\x00y\x00_\x00o\x00p\x00t\x00i\x00o\x00n\x00s\x00_\x00s\x00e\x00a\x00r\x00c\x00h\x00_\x00b\x00u\x00t\x00t\x00o\x00n\x00"\x00 \x00=\x00 \x00"\x00L\x00a\x00u\x00n\x00c\x00h\x00 \x00t\x00h\x00e\x00 \x00s\x00e\x00a\x00r\x00c\x00h\x00"\x00;\x00'
s_2 = '"itinerary_options_search_button" = "Launch the search";'

def null_cleaner(string):
    new_string = ""
    for char in string:
        if char != "\x00":
            new_string += char
    return new_string

print(null_cleaner(s_1) == null_cleaner(s_2))

A little bit less robust way of doing this is to simply splice the string to remove every other character (which happens to be \\x00 ):

s_1 = '\x00"\x00i\x00t\x00i\x00n\x00e\x00r\x00a\x00r\x00y\x00_\x00o\x00p\x00t\x00i\x00o\x00n\x00s\x00_\x00s\x00e\x00a\x00r\x00c\x00h\x00_\x00b\x00u\x00t\x00t\x00o\x00n\x00"\x00 \x00=\x00 \x00"\x00L\x00a\x00u\x00n\x00c\x00h\x00 \x00t\x00h\x00e\x00 \x00s\x00e\x00a\x00r\x00c\x00h\x00"\x00;\x00'
s_2 = '"itinerary_options_search_button" = "Launch the search";'

print(s_1[1::2] == s_2)

Answer 2

... encoded in ASCII.

 [lots of NULs] 

Nope.

>>> '\x00"\x00i\x00t\x00i\x00n\x00e\x00r\x00a\x00r\x00y'.decode('utf-16be')
u'"itinerary'

Of course, your data has an extra NUL that will break it. Once you clean that up you should be able to decode it with no problem.