Re: Converting MBCS project to UNICODE compliant.. Pros and Cons

Ulrich Eckhardt <>
Wed, 04 Feb 2009 09:27:54 +0100
sachin wrote:

using TCHAR or _T will only help to save code modification time when you
switch back to ASCII. in my case i will never go back to ASCII version as
internationalization is basic requirement . My concern was should switch
all my data structure into wstring or WCHAR ? or should i do it
selectively only for needed business object classes .

Make a decision what kind of string type you actually need. For UI texts,
that would be Unicode and using WCHAR with a UTF-16 encoding actually does
the job mostly. I say mostly, because there are e.g. 'surrogate pairs' that
are not as easily handled under UTF-16, but if you are not modifying
strings that should not be an issue.

For example :
I have STD::map<int, string> where string is a hash Code of some files
now we do not need to keep this map in unicode version std::map<int,
wstring> because hash value will always be within 0 - F ( ASCII )
this table to huge in size ( say for all the files which i am crawling
from desktop machine ) Should i keep this in ASCII form or converting
it to Unicode string wont eat much memory ?

I don't think you will die from converting it to WCHAR, but the data
structure doesn't require it, so stay with the most simple of solutions
i.e. std::string. If that table is really that huge, you might actually
benefit from using a fixed-size char array, because
1. it fits the requirements (I guess)
2. it avoids dynamic allocations which are expensive both in terms of memory
overhead and computational time
3. it avoids dereferencing a pointer, which puts higher load on your CPU to
memory interface.
However, those are optimisations.

"I did notice files that I saved to disk got larger [...]"

This is a result of not making a decision on the file format but rather
dumping in-memory structures to disk as they are.

"[...] so I typically convert to and from UTF-8 when writing text files."

And this is a solution for text files. Other solutions for more complex data
structures are e.g. XML or JSON.


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