再次求助啊
下面程序不能编译，求解

#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;
}

[解决办法]
ifstream& open_file(ifstream&, const string&);
只声明，没有定义
加上后可以编译通过，但是逻辑貌似有问题，要睡觉了...

C/C++ code

#include <map>#include <vector>#include <iostream>#include <fstream>#include <string>#include <cstring>#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;using namespace std;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;} ifstream& open_file(ifstream& ifs, const string& str){    //char filename[40]="";    //strcpy(filename,str.c_str());    ifs.open(str.c_str());    return ifs;} 
 
[解决办法]
把楼上的代码拷贝回去慢慢调试去吧
[解决办法]
这个作为一个程序员，最先要学会的是单步调试。。。。你自己调试一下试试。。。。