Re: [Boost-users] replace_all_regex on c-string help

From: John Maddock (john_at_[hidden])
Date: 2006-08-02 05:33:22

> I got the string (char*s), which is too big (>10M), from an external
> library, it's too slow to convert the raw string to std::string before
> it is handled by replace_all_regex

Here's your fundamental problem: regex does not do in-place search and 
replace.

Further:

* Any attempt to do so on a fixed size buffer runs the risk of buffer 
over-run errors, the *best* that you might hope for is that the application 
only crashes infrequently!
* In-place replace is often slower than copying: all that shuffling of 
characters around in the buffer as the size of each matched section is 
adjusted is a time-killer.  In the worst case it's O(N^2), where as copying 
is amortized O(N).

You can clearly use your C-string as the source for the regex search and 
replace, but the destination must be somewhere else.  Could be a string, 
could be a vector<char>, could be a stream, could be.... whatever.

John.