期望eof，而不是eof附近的任意数据

我试图发现我正在写入特定数据的文件中不需要的尾随结束数据的原因，并且不相信我在写入文件时犯了错误。

输出如下:

building     room_numbr   capacity
packard    | 101        | 500        |
painter    | 514        | 10         |
ÿÿÿÿÿÿÿÿÿÿ | Attempt to seek file pointer error

Attempt to seek file pointer error是正常的，因为它表示当试图在无效流上移动文件指针时抛出异常。然而，ÿÿÿÿÿÿÿÿÿÿ不是正常的，也不是固定大小的文件格式，使用10或20字节来写数据。

创建文件:

BinarySearchFile::BinarySearchFile(std::string file_name){
    // concatenate extension to fileName
    file_name += ".dat";
    // form complete table data filename
    data_file_name = file_name;
    // create or reopen table data file for reading and writing
    binary_search_file.open(data_file_name,  std::ios::out | std::ios::in | std::ios::app); 
    if(!binary_search_file.is_open()){
        binary_search_file.clear();
        binary_search_file.open(data_file_name, std::ios::out);
        binary_search_file.close();
        binary_search_file.open(data_file_name, std::ios::out | std::ios::in | std::ios::app);
    }
    try{
        if(binary_search_file.fail()){
            throw CustomException("Unspecified table data file error");
        }
    }
    catch (CustomException &custom_exception){  // Using custom exception class
        std::cout << custom_exception.what() << std::endl;
        return;
    }   
}

写入文件

void BinarySearchFile::writeT(std::string attribute){
try{
    if(binary_search_file){
        for(auto start = attribute.begin(); start != attribute.end();  ++start){
            binary_search_file.put(' ');
            binary_search_file.put(*start);
        }
        binary_search_file.flush();
        /*
        attribute.resize(attribute.length() * 2);
        const char *write_this = attribute.data();
        binary_search_file.write(write_this, attribute.length());
        */
    }else if(binary_search_file.fail()){
        throw CustomException("Attempt to write attribute error");
    }
}
catch(CustomException &custom_exception){  // Using custom exception class
    std::cout << custom_exception.what() << std::endl;
    return;
}
}

读取数据文件:

   std::string BinarySearchFile::readT(long file_pointer_location, long size_of_data) 
{
try{
    if(binary_search_file){
        std::string data = "";
        binary_search_file.seekp(file_pointer_location);
        binary_search_file.seekg(file_pointer_location);
        while (size_of_data > 0 ){
            binary_search_file.get();
            data += binary_search_file.get();
            size_of_data -= 2;
        }
        /*
        char data[20];
        binary_search_file.seekp(filePointerLocation);
        binary_search_file.seekg(filePointerLocation);
        binary_search_file.read(data, sizeOfData);
        */
        return data;
    }else if(binary_search_file.fail()){
        throw CustomException("Attempt to read attribute error");
    }
}
catch(CustomException &custom_exception){  // Using custom exception class
    std::cout << custom_exception.what() << std::endl;
}
}

读取文件并将结果打印到屏幕上的代码:

while(true){
    //reinitialize the catalog pointer to the beginning 
    catalog->setPointerBegin();
    //display data
    do{
        if (boost::iequals((domain = catalog->getAttributeDomain()), "string")){
            if(dataFile->binary_search_file_status()){
                std::cout << dataFile->read_data(filePointer, 20) << " | ";
                if (!writer_.fail())
                    writer_ << dataFile->read_data(filePointer, 20) << " | ";
            }
            else{
                std::cout << "n";
                if (!writer_.fail())
                    writer_ << "n";
                        return true;
                }
                // update the file pointer
                filePointer += 20;
                dataFile->set_file_pointer(filePointer);
            }
            else{
                if(dataFile->binary_search_file_status()){
                    std::cout << dataFile->read_data(filePointer, 10);
                    if (!writer_.fail())
                        writer_ << dataFile->read_data(filePointer, 10);
                    for(int i = 0; i < 5; i++){
                            std::cout << " ";
                            if (!writer_.fail())
                                writer_ << " ";
                        }
                        std::cout << " | ";
                        if (!writer_.fail()){
                            writer_ << " | ";
                    }
                }
                else{
                    std::cout << "n";
                    if (!writer_.fail()){
                        writer_ << "n";
                    }
                    return true;
                }
                // update the file pointer
                filePointer += 10;
                }       

            } while(catalog->traverseForward() != nullptr);
            std::cout << "n";
            if (!writer_.fail())
                writer_ << "n";
    }
}