cpp primer 验证 p318页

/*** Copyright (C) WWQ All rights reserved.*/#include <map>#include <stdexcept>#include <string>#include <iostream>#include <fstream>#include <sstream>using namespace std;//open_file() 函数ifstream & open_file(ifstream& in, const string& file){in.close();in.clear();in.open(file.c_str());return in;}//单词转换程序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 first_word = 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 (first_word){first_word = false;}else{cout << " ";}cout << word;}cout << endl;}return 0;}