Aminos Aminos - 2 months ago 13
C++ Question

Replacing characters by a modified version of them in a string

I want to replace the characters below (or sub-strings for the && and ||)in an input string with regex replace

+ - ! ( ) { } [ ] ^ " ~ * ? : \ && ||


How can I write this request in the construction of the std::regex ?

For example if I have

"(1+1):2"


I want to have an input of :

"\(1\+1\)\:2"


The final code looks something like this :

std::string s ("(1+1):2");
std::regex e ("???"); // what should I put here ?

std::cout << std::regex_replace (s,e,"\\$2"); // is this correct ?

Answer

You can use std::regex_replace with capture:

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

using namespace std;

int main() {
    regex regex_a("(\\+|-|!|\\(|\\)|\\{|\\}|\\[|\\]|\\^|\"|~|\\*|\\?|:|\\\\|&&|\\|\\|)");
    cout << regex_replace("(1+1):2", regex_a, "\\$0") << endl;
}

This prints

$ ./a.out 
\(1\+1\)\:2