从文件读取（ifstream）和写入文件（ofstream）-编码问题

Question

Note: I'm rather a c++ rookie.

I've the following problem:

I read from a file and want to replace string parts with other string parts. Simple task, should be easy to do. I did some experiments with setmode, but without success. I googled also imbue, but it didn't help me either.

There might be minor code issues, but please focus on the problem. The test data for conversion is given below:

int main(int argc, char** argv) {
    stringstream strs;

    //Choose output file
    ofstream ofile;
    string filename;
    cout << "Ausgabepfad eingeben" << endl;
    cin >> filename;
    ofile.open(&filename[0]);

    //Choose input file
    ifstream ifile;
    cout << "Quellpfad eingeben" << endl;
    cin >> filename;
    ifile.open(&filename[0]);

    //Choose decoding - doesnt work, I know - That was for experiments
    int mode = 0;
    cout << "Decoding wählen\n1 für _O_TEXT\n2 für _O_BINARY\n3 für _O_U16TEXT\n4 für _O_U8TEXT\n5 für _O_WTEXT" << endl;
    cin >> mode;
/*    switch(mode){
        case 1:
            _setmode (_fileno(ifstream), _O_TEXT);
        break;
        case 2:
            _setmode (_fileno(ifstream), _O_BINARY);
        break;
        case 3:
            _setmode (_fileno(ifstream), _O_U16TEXT);
        break;
        case 4:
            _setmode (_fileno(ifstream), _O_U8TEXT);
        break;
        case 5:
            _setmode (_fileno(ifstream), _O_WTEXT);
        break;
        default:
            cerr << "ungültige Codierung gewählt"
    }
*/    

    //Choose search string and replacement string
    ifile.seekg(0); //not necessary, I know
    string searchstr = "";
    cout << "Suchstring eingeben" << endl;
    cin >> searchstr;
    string fillstr;
    cout << "Ersetzungsstring eingeben" << endl;
    cin >> fillstr;
    cout << fillstr;
    int marker = 0;
    if(searchstr.length()<1){
        return 0;
    }

    //actual program
    while(!ifile.eof()){
        int counter = 0;
        ifile.seekg(marker);
        char current = ifile.get();
        if(current==searchstr[0]){ //if the first search letter matches, seet, if the others do.
            marker++;
            counter++;
            for(int i = 1; i < searchstr.length(); i++){
                ifile.seekg(marker);
                if(ifile.get()==searchstr[i]){
                    counter++;
                    marker++;
                }else{
                    marker-i;
                    break;
                }
            }
            if(counter == searchstr.length()){
                ofile << fillstr;
                cout << endl;
            }
        }else{
            ofile << ifile.get();
            cout << ifile.get();
        }
        marker++;

    }

    ifile.close();
    ofile.close();
    cout << endl;
    return 1;
}

The following string

|-

should be replaced by

\n

The text (sample) is:

|[[Allgemeines Deutsches Kommersbuch:1|1]] 
|1 
|[[Abend wird's, des Tages (Körner)]] 
|[[Die Eichen (Körner)]]
|-
|[[Allgemeines Deutsches Kommersbuch:2|2]] 
|2 

The program runs, but it doesn't work. The output is lots of numbers without any sense.

Answer 1

The output is lots of numbers without any sense.

The call ifile.get() returns a value of type int_type . Thus << outputs all these integer values.

Replace

ofile << ifile.get();

(doing formatted output of integers) with

ofile << char( ifile.get() );

or (preferred, using unformatted input and output)

ofile.put( ifile.get() );

Answer 2

It's almost always a better idea to express the problem in terms of standard streams, iterators and algorithms:

#include <iostream>
#include <string>
#include <sstream>
#include <algorithm>

// lets get the logic right in terms of streams


void replace_all(std::ostream& dest, std::istream& source, 
                 const std::string& search_for, const std::string& replace_with)
{
    std::string line;
    while (std::getline(source, line)) {
        auto ipos = line.begin();
        while (ipos != line.end())
        {
            ipos = std::search(ipos, line.end(), search_for.begin(),
                               search_for.end());
            if (ipos != line.end())
            {
                auto start_index = std::distance(line.begin(), ipos);
                line.replace(ipos, std::next(ipos, search_for.length()), 
                             replace_with);
                ipos = std::next(line.begin() + start_index + replace_with.length());
            }
        }
        dest.write(line.data(), line.size());
        dest.put('\n');
    }

}

// now test
int main()
{
    std::string search_for = "|-";
    std::string replace_with = "";

    std::istringstream source_stream("|[[Allgemeines Deutsches Kommersbuch:1|1]]\n"
                                     "|1\n"
                                     "|[[Abend wird's, des Tages (Körner)]]\n"
                                        "|[[Die Eichen (Körner)]]\n"
                                        "|-\n"
                                        "|[[Allgemeines Deutsches Kommersbuch:2|2]]\n"
                                     "|2\n");

    std::ostringstream dest_stream;

    replace_all(dest_stream, source_stream, search_for, replace_with);

    std::cout << dest_stream.str();

    return 0;
}

// todo: write a new main which asks for filenames, builds ifstreams and ofstreams, and calls replace_all()

expected output:

|[[Allgemeines Deutsches Kommersbuch:2|2]]
|2
Jewels-MacBook-Pro:play richardh$ ./replace.cpp
|[[Allgemeines Deutsches Kommersbuch:1|1]]
|1
|[[Abend wird's, des Tages (Körner)]]
|[[Die Eichen (Körner)]]

|[[Allgemeines Deutsches Kommersbuch:2|2]]
|2