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++Ↄ is basically C++ but every program must be written in one line and in reverse order.

A standard-compliant ++Ↄ preprocessor needs to split the source code into lines by whitespace characters and then reverse the line order.


Here is a Hello World program written in ++Ↄ:

} std::cout<<"Hello,\x20World!\n"; main(){ int #include<iostream>

And this is what the Hello World program should look like after preprocessing:

int main()
    std::cout<<"Hello, World!\n";
    return 0;


Here is a simple ++Ↄ preprocessor written in C++:

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>

std::string preprocess(auto &&is, std::string _code = {}, std::string _res = {}) {
  std::istringstream iss{ (std::getline(is, _code), std::move(_code)) };
  while (iss >> _code) _res = _code + "\n" + _res;
  return _res;

int main(int argc, char *argv[]) {
  if      (argc >= 4) std::cout << "Usage: " << argv[0] << " [input file] [output file]\n";
  else if (argc == 3) std::ofstream(argv[2]) << preprocess(std::ifstream(argv[1]));
  else if (argc == 2) std::cout << preprocess(std::ifstream(argv[1]));
  else                std::cout << "Enter ++Ↄ source code:\n" << preprocess(std::cin);