Replace the text numbers string in a txt file using C++.. Help Me..

For example:
 Before Document: 
        hai hello my daily salary is two thousand and five and your salary is five billion. my age is twenty-five.

After Document:
        hai hello my daily salary is # and your salary is #. my age is  #.

All the text numbers and i put the # symbol.. Please give me the correct code..

I am trying this code: 

#include <iostream>
#include <fstream>
#include <string>
 
using namespace std;
 
ifstream myfile_in ("sample.txt");
ofstream myfile_out ("Lista2.txt");
string line;
 
void find_and_replace( string &source,  string find, string replace ) { 
 
    size_t j;
 
    for ( ; (j = source.find( find )) != string::npos ; ) {
        source.replace( j, find.length(), replace );
        }
 
        myfile_out << source <<endl;
        cout << source << endl;
        }
 
int main () {
 
  if (myfile_in.is_open())
  {
    int i = 0,j;
    //string strcomma ;
   // string strspace ;
 
    while (! myfile_in.eof() )
    {
 
      getline (myfile_in,line);
 
	  string strcomma= "two";
	  string strspace = "#";
	
 
      find_and_replace( line , strcomma , strspace );
  
   
      i++;
 
    }
 
    myfile_in.close();
 
  }
 
  else cout << "Unable to open file(s) ";
 
  system("PAUSE");
  return 0;
}