Re: Where is String class? (original) (raw)

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• To: oliva at dcc dot unicamp dot br (Alexandre Oliva)
• Subject: Re: Where is String class?
• From: Joe Buck
• Date: Wed, 7 Apr 99 9:22:46 PDT
• Cc: ildar at faki-campus dot mipt dot ru, egcs at egcs dot cygnus dot com

On Apr 7, 1999, Ildar Mulyukov ildar@faki-campus.mipt.ru wrote:

substitute MFC's CString class. As I can see "string" class from std/bastring.h has less functionality then I need.

I don't know what you get get with MFC's CString, but `string' is Standard C++, likely to work with any C++ compiler, so it's probably the way to go.

I occasionally must deal with MFC stuff.

The only things MFC's CString provides that string does not are:

• trimming of whitespace
• case conversion
• CString::Format

The first two are trivial to do yourself; the third lets you do sprintf-style conversion without risk of overflow and is nice to have. Is that what you need? It could be written as a non-member function, e.g.

void sprintf(string& buffer, const char* format, ...);

Our real problem is that we don't have stringstream in libstdc++ 2.

CString suffers from a common programming error that results in poor performance. Consider the following code:

CString n_copies_of(const CString& foo, unsigned n) { CString tmp; for (unsigned i = 0; i < n; i++) tmp += foo; return tmp; }

This function is O(n^2), not O(n). The reason is that each += causes a reallocation and copy of the existing string. Microsoft applications are full of this kind of thing (quadratic performance on tasks that can be done in linear time) -- on the other hand, we should be thankful, as it's created such a big market for high-end ix86 hardware. :-)

If you replace CString with string in the above function, the performance is O(n).

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    * From: Alexandre Oliva