word_transform.cpp

C++Primer 第四版 包括windows 平台下各章的例子程序

/*
 * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
 * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 * 
 * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
 * 
 * 
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 * 
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address: 
 * 
 * 	Pearson Education, Inc.
 * 	Rights and Contracts Department
 * 	75 Arlington Street, Suite 300
 * 	Boston, MA 02216
 * 	Fax: [phone]
*/ 

#include <map>
#include <vector>
#include <iostream>
#include <fstream>
#include <string>
#include <stdexcept>
#include <sstream>

using std::map; using std::string; using std::vector;
using std::ifstream; using std::cout; using std::endl;
using std::getline; using std::make_pair;
using std::runtime_error; using std::istringstream;

ifstream& open_file(ifstream&, const string&);

int main(int argc, char **argv)
{
    // map to hold the word transformation pairs: 
    // key is the word to look for in the input; value is word to use in the output
    map<string, string> trans_map;
    string key, value;

    if (argc != 3)
        throw runtime_error("wrong number of arguments");

    // open transformation file and check that open succeeded
    ifstream map_file;
    if (!open_file(map_file, argv[1]))
        throw runtime_error("no transformation file");
    // read the transformation map and build the map 
    while (map_file >> key >> value) 
        trans_map.insert(make_pair(key, value));
{
    // ok: let's display it
    map<string, string>::iterator map_it = trans_map.begin();

    //cout << "Here is our transformation map: \n\n";
    while (map_it != trans_map.end()) {
        cout << "key: "   << map_it->first; 
        if (map_it->first.size() == 1)
            cout << "       ";
        if (map_it->first.size() == 3)
            cout << "     ";
        else if (map_it->first.size() == 4)
            cout << "    ";
        else if (map_it->first.size() == 5)
            cout << "   ";
        cout << "value: " << map_it->second << endl;
        ++map_it;
    }
    cout << "\n\n";

    {  // this block just produces the vector so that we can print it
       // for the book
    cout << "Here is our original string input:\n\n";
    // read some text to transform
    ifstream input;
    if (!open_file(input, argv[2]))
        throw runtime_error("no input file");
    string word;
    while (getline(input, word)) 
         cout << word << endl;
    cout << "\n\n\n";
    input.close(); input.clear();
    }
}

    // ok, now we're ready to do the transformations
    // open the input file and check that the open succeeded
    ifstream input;
    if (!open_file(input, argv[2]))
        throw runtime_error("no input file");

    string line;   // hold each line from the input

    // read the text to transform it a line at a time
    while (getline(input, line)) {
        istringstream stream(line);  // read the line a word at a time
        string word;
        bool firstword = true;  // controls whether a space is printed 
        while (stream >> word) {
           // ok: the actual mapwork, this part is the heart of the program
           map<string, string>::const_iterator map_it =
                               trans_map.find(word);

           // if this word is in the transformation map
           if (map_it != trans_map.end()) 
               // replace it by the transformation value in the map
               word = map_it->second;  
           if (firstword)
               firstword = false;
           else
               cout << " ";  // print space between words
           cout << word;
        }
        cout << endl;        // done with this line of input
    }
    return 0;
}