Передача аргументов функции

#include <iostream>
#include <map>
#include <string>
#include <cctype>
#include <fstream>
#include <sstream>
 
 
using std::cout;
using std::cin;
using std::map;
using std::string;
using std::runtime_error;
using std::ifstream;
using std::getline;
using std::istringstream;
using std::endl;
 
ifstream& open_file(ifstream &in, const string &file)
{
    in.close();
    in.clear();
    in.open(file.c_str());
    return in;
}
 
int main(int argc, char  **argv) 
{
    map<string, string> trans_map;
    string key, value;
    if (argc != 3)
        throw runtime_error("Wrong number of arguments");
    ifstream map_file;
    if (!open_file(map_file, argv[1]))
        throw runtime_error("no transformation file");
    while (map_file >> key >> value)
        trans_map.insert(make_pair(key, value));
    ifstream input;
    if (!open_file(input, argv[2]))
        throw runtime_error("no input file");
    string line;
    while (getline(input, line)) {
        istringstream stream(line);
        string word;
        bool firstword = true;
        while (stream >> word) {
            map<string, string>::const_iterator map_it = trans_map.find(word);
            if (map_it != trans_map.end())
                word = map_it->second;
            if (firstword)
                firstword = false;
            else 
                cout << " ";
            cout << word;
        }
        cout << endl;
    }
    return 0;
}

#include <iostream>
#include <map>
#include <string>
#include <cctype>
#include <fstream>
#include <sstream>
 
 
using std::cout;
using std::cin;
using std::map;
using std::string;
using std::runtime_error;
using std::ifstream;
using std::ofstream;
using std::getline;
using std::stringstream;
using std::endl;
 
ifstream& open_file(ifstream &in, const string &file)
{
    in.close();
    in.clear();
    in.open(file.c_str());
    return in;
}
 
int main(int argc, char  **argv) 
{
    map<string, string> trans_map;
    string key, value;
    //if (argc != 3)
        //throw runtime_error("Wrong number of arguments");
    ifstream map_file;
    if (!open_file(map_file, "1.txt"/*argv[1]*/))
        throw runtime_error("no transformation file");
    while (map_file >> key >> value)
        trans_map.insert(make_pair(key, value));
    ifstream input;
    if (!open_file(input, "2.txt"/*argv[2]*/))
        throw runtime_error("no input file");
    
    stringstream stream;
    stream << input.rdbuf();
    input.close();
 
    ofstream fout("2.txt");
   
    string word;
    while (stream >> word) 
    {
        map<string, string>::const_iterator map_it = trans_map.find(word);
        if (map_it != trans_map.end())
        {
            word = map_it->second;
            fout << word << ' ';
        }
        else 
            fout << word << ' ';
    }
    fout.close();
    cout << endl;
    
    return 0;
}