Question

I have a file which has text like this:

#1#14#ADEADE#CAH0F#0#0.....

I need to create a code that will find text that follows # symbol, store it to variable and then writes it to file WITHOUT # symbol, but with a space before. So from previous code I will get:

1 14 ADEADE CAH0F 0 0......

I first tried to did it in Python, but files are really big and it takes a really huge time to process file, so I decided to write this part in C++. However, I know nothing about C++ regex, and I’m looking for help. Could you, please, recommend me an easy regex library (I don’t know C++ very well) or the well-documented one? It would be even better, if you provide a small example (I know how to perform transmission to file, using fstream, but I need help with how to read file as I said before).

Answer 1

This looks like a job for std::locale and his trusty sidekick imbue:

#include <locale>
#include <iostream>


struct hash_is_space : std::ctype<char> {
  hash_is_space() : std::ctype<char>(get_table()) {}
  static mask const* get_table()
  {
    static mask rc[table_size];
    rc['#'] = std::ctype_base::space;
    return &rc[0];
  }
};

int main() {
  using std::string;
  using std::cin;
  using std::locale;

  cin.imbue(locale(cin.getloc(), new hash_is_space));

  string word;
  while(cin >> word) {
    std::cout << word << " ";
  }
  std::cout << "\n";
}