boost::regex_replace-CodePudding

Currently I have a problem with boost :: regex, I need to find the appropriate word և replace. with the corresponding word. My code now looks like this.

std::string name = ptap;
std::string name_regex = "\\b"   name   "\\b"; 
boost::regex reg(name_regex);
checks_str = boost::regex_replace( checks_str, reg, alias_name );

There are words in the file that look like "ptap.power" because regex reads the dot as any character. The initial part of this word (ptap) changes, which I do not need. How to fix this?

CodePudding user response：

You can prevent a match if there is a dot after a word:

#include <boost/regex.hpp>
#include <string>
#include <iostream>

int main()
{
    std::string str = "ptap ptap.power";
    std::string name = "ptap";
    std::string rep = "pplug";
    std::string regex_name = "\\b"   name   "\\b(?!\\.)";
    boost::regex reg(regex_name);
    str = boost::regex_replace(str, reg, rep);
    std::cout << str << std::endl;
    return 0; 
}

See the C demo.

The (?!\.) is a negative lookahead that fails the match if there is a . char immediately to the right of the current location.

To avoid matching the keyword if there is a dot before, add a negative lookbehind:

std::string regex_name = "\\b(?<!\\.)"   name   "\\b(?!\\.)";