#include <iostream>
#include <string>
#include <regex>
 
int main()
{
    std::regex pattern { "abc" }; // on recherche le motif "abc"
    std::string target { "abcdefabc" };
    std::string replacement { "123" };
    std::string result = std::regex_replace(target, pattern, replacement);
    std::cout << result << std::endl;
}