regex_replace flag to ignore multiline?

Question

DEMO

#include <iostream>  
#include <regex>  
  
int main()  
{  
    std::string text = R"(blue  
red  
green  
)";  
    std::regex re("^red+\n");  
    std::string str = std::regex_replace(text, re, "");  
    std::cout << str;  
  return 0;  
}  

The compile of the demo above the regex doesn't replace red I think by default it doesn't do a multiline search/replace? while on visual studio the exactly same code red is replaced.

How could I make Visual Studio behave the same? I mean, doesn't replace things on multiline if doesn't ask to.

While searching about I found this in MSDN docs: Regex Flags.

I wonder if I need to specify any special flag? I read the flags in the link but I still couldn't figure out which to use.

Answer 1

Hi @Marcus ,

If you want visual studio to get the same result as the demo, you need to use match_continuous, which specifies that the expression must match a sub-sequence that begins at first.

Sample Code:

std::regex re("^red+\n");  
std::string str = std::regex_replace(text, re, "",std::regex_constants::match_continuous);  

Result:

Best regards,

Elya

---

If the answer is the right solution, please click "Accept Answer" and upvote it.If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.