Re: [Boost-users] [C++] Boost::Regex beginner question

19 Dec 2008

      thank you for the response. unfortunately, we've tried to use the
regex_replace function, but it gave an unexpected error:
'regex_replace' : undeclared identifier
we used it in the following way:

#include 
#include 
#include 
#include 
#include <iostream>
#include <string>
#include 

using namespace std;
using namespace boost;

int main(int argc, char* argv[])
{
        boost::regex e("\<\<(\.\*?)\>\>");
        string str = "cavalo \<\\> olavac";
        cout << regex_replace(str, e, "cavalo $1 olavac");
        return 0;
}

NOTE: the Regex++ we are using was downloaded from the original
author's site, not entirely with the Boost library. we can't
understand this error. if we downloaded and installed it according to
the installation instructions for VC++, how can a function be missing?

2008/12/18 Alan M. Carroll :
...
Let's say you had an input form that was similar to that of Boost.Format
except that you could specify type information by appending a '|' followed
by the type, e.g. "%1|int%", and you could name the inserts as well as use
numbers (e.g., "%count|int%"). After some preprocessing to pull out the
types, you then wanted to strip the type specifiers to make the string
Boost.Format compliant. So '%1|int%" would become "%1%" and "%2%" would
remain unchanged (because type specifiers are not required).
// This matches the insert strings, e.g. "%1|int%" with subexpressions for
the number or name
boost::regex const RXP_INSERT(
"%(?:(\\d+)|([_a-z][_a-z0-9]*))(?:[|]([_a-z][_:a-z0-9]*))?%" ,
boost::regex_constants::icase);
// ...
// Time to strip the type specifiers. We match each insert then replace with
the first two groups,
// exactly one of which will be set ($1 if a number, $2 if name)
            msgText = boost::regex_replace(msgText, RXP_INSERT, "%$1$2%");
// No more type specifiers. Changing names to numbers is a bit more complex
but this should illustrate
// the principle.
At 04:41 PM 12/18/2008, P.C. wrote:
my doubt is the following: I want to know how to do search and replace
regexp operations, like it can be done in Perl by using groups (expressions
surrounded by parentheses), which allow to select the substrings, matched by
the regexp, in the form of $1, $2
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