Re: [Boost-users] Strange (wrong?) behavior of boost::regex_replace()

From: Andrew Holden (aholden_at_[hidden])
Date: 2007-11-14 14:26:34

Peter Klotz wrote:
> The program below gives different output in Boost 1.32.0 compared to
> 1.33.1 and 1.34.1.
> 
> In my opinion "R_Test" would be the correct result and therefore Boost
> 1.33.1 and 1.34.1 would be wrong.
> 
> Can anyone clarify this issue?
> 
> Best regards, Peter.
> 
> #include <iostream>
> #include <boost/regex.hpp>
> 
> int main()
> {
>    // Boost 1.32.0: "R_Test"
>    // Boost 1.33.1 and 1.34.1: "R_TestR_"
>    std::cout <<
> boost::regex_replace(std::string("Test"),boost::regex("(.*)"),
> "R_$1") << std::endl;    return 0; }

I would expect the behavior in Boost 1.33+.  The regex first matches the
full string "Test", then it matches the empty string at the end.

Try changing the expression to "(.+)" to match 1 or more characters, or
"^(.*)" to match only the text at the beginning of the string.