动态分配的聊天数组打印丢失的数据&空

Question

我正在使用xerces解析XML，并构建一个内部结构，稍后我可以遍历它。

作为此解析的一部分，我遇到了如下所示的可变数量的<Field_Delimited>元素：

<Field_Delimited>
<name>some_value</name>
<data_type>ASCII_Real</data_type>
<unit>some_value</unit>
<description>some_value</description>
</Field_Delimited>

内存中将表示这些字段的结构(称为file_observational_area )是在全局文件级别声明的，参见相关片段，最相关的方法是get_data()

file_observational_area * _file_observational_area = NULL;

    int main(int argc, char* args[]) {

        //pass in as console argument 
        char* xmlFile = args[1];

        //initialize  file_observational_area
        _file_observational_area = allocate_file_observational_area(_file_observational_area, 1);
        //actual data
        field_data_value * _field_data_values_array = NULL;

    try {
        parser->parse(xmlFile);

        DOMDocument* dom = parser->getDocument();

        DOMNodeList * dom_node_list = dom->getChildNodes();

        for (unsigned int i = 0; i < dom_node_list->getLength(); i++) {

            walk_DOM(dom_node_list->item(i), _file_observational_area);
        }

        get_data(_file_observational_area, xmlFile, 0, 0, 0, _field_data_values_array);



    } catch (const XMLException& toCatch) {
        char* message = XMLString::transcode(toCatch.getMessage());
        cout << "Exception message is: \n"
                << message << "\n";
        XMLString::release(&message);
        return -1;
    }

    }

walk_dom()相关片段，它调用parse_dom():

void walk_DOM(DOMNode * dom_node, file_observational_area * _file_observational_area) {



    if (_file_observational_area) {
        _file_observational_area = parse_dom(dom_node, _file_observational_area);
}

parse_dom()函数相关片段：

 /*<Field_Delimited>*/
                                                        if (XMLString::equals(currentElement->getNodeName(), XMLString::transcode("Field_Delimited"))) {

                                                            /*<Field_Delimited>
                                                           <name>enc4</name>
                                                           <data_type>ASCII_Real</data_type>
                                                           <unit>rad</unit>
                                                           <description>Joint 4 encoder counts [RA_DOF]</description>
                                                           </Field_Delimited>*/

                                                            /*<Field_Delimited>*/
                                                            XMLCh* tag_Field_Delimited_name = XMLString::transcode("name");
                                                            string tag_Field_Delimited_name_val;
                                                            XMLCh* tag_Field_Delimited_data_type = XMLString::transcode("data_type");
                                                            string tag_Field_Delimited_data_type_val;
                                                            XMLCh* tag_Field_Delimited_unit = XMLString::transcode("unit");
                                                            string tag_Field_Delimited_unit_val;
                                                            XMLCh* tag_Field_Delimited_description = XMLString::transcode("description");
                                                            string tag_Field_Delimited_description_val;
                                                            DOMElement * field_delimited_element = NULL;
                                                            cout << "<Field_Delimited> DETECTED\n";


                                                            DOMNode * child = currentElement->getFirstElementChild();


                                                            while (NULL != child) {


                                                                if (DOMNode::ELEMENT_NODE == child->getNodeType()) {
                                                                    if (XMLString::equals(tag_Field_Delimited_name, child->getNodeName())) {
                                                                        _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].name = XMLString::transcode(child->getTextContent());
                                                                        //strcpy(_file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].name, XMLString::transcode(child->getTextContent()));
                                                                        cout << "Debug: tag_Field_Delimited_name_val:" << _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].name << "\n";
                                                                    }
                                                                    if (XMLString::equals(tag_Field_Delimited_data_type, child->getNodeName())) {
                                                                        _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].data_type = XMLString::transcode(child->getTextContent());
                                                                        //strcpy(_file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].data_type, XMLString::transcode(child->getTextContent()));
                                                                       cout << "Debug: tag_Field_Delimited_data_type_val:" << _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].data_type << "\n";
                                                                    }
                                                                    if (XMLString::equals(tag_Field_Delimited_unit, child->getNodeName())) {
                                                                        _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].unit = XMLString::transcode(child->getTextContent());
                                                                        // strcpy(_file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].unit, XMLString::transcode(child->getTextContent()));
                                                                        cout << "Debug: tag_Field_Delimited_unit_val:" << _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].unit << "\n";
                                                                    }
                                                                    if (XMLString::equals(tag_Field_Delimited_description, child->getNodeName())) {
                                                                        _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].description = XMLString::transcode(child->getTextContent());
                                                                         //strcpy(_file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].description, XMLString::transcode(child->getTextContent()));
                                                                        cout << "Debug: tag_Field_Delimited_description_val:" << _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].description << "\n";
                                                                    }
                                                                }


                                                                child = child->getNextSibling();

                                                            }//end while <Field_Delimited> has siblings

                                                        }//end  /*<Field_Delimited>*/



}

日志显示了 parse_dom() 的预期行为，我可以通过 XMLString::transcode(child->getTextContent()) &来获得正确的值，使用 _file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].name = XMLString::transcode(child->getTextContent());设置值。

问题所在:然而，在void get_data()**，中，char的值丢失或损坏，请参阅相关片段**：

                                                            for (int field_record_index = 0; field_record_index < _file_observational_area->_table_delimited->_record_delimited->fields; field_record_index++) {
                                                                if (NULL != _file_observational_area->_table_delimited->_record_delimited->_field_delimited) {

                                                                    cout << "<Field_Delimited> number:" << field_record_index << "\n";

                                                                    //MISSING or corrupted name
                                                                    cout << "name :" << _file_observational_area->_table_delimited->_record_delimited->_field_delimited[field_record_index].name << "\n";

                                                                    //MISSING or corrupted datatype
                                                                    cout << "data_type:" << _file_observational_area->_table_delimited->_record_delimited->_field_delimited[field_record_index].data_type << "\n";
                                                                    //MISSING or corrupted unit
                                                                    cout << "unit:" << _file_observational_area->_table_delimited->_record_delimited->_field_delimited[field_record_index].unit << "\n";
                                                                    //MISSING or corrupted description 
                                                                    cout << "description:" << _file_observational_area->_table_delimited->_record_delimited->_field_delimited[field_record_index].description << "\n";

                                                                                                                                }

这就是我为动态字符串分配内存的方式：

 /*=============================================================================
    Function        malloc_field_delimited
    Description:    allocated memory for _record_delimited->_field_delimited
     *                  dynamic array 
    References:       
    Inputs:         
    Output:            
    ==========================================================*/
    field_delimited * malloc_field_delimited(field_delimited * _field_delimited, int number_of_fields) {

         _field_delimited = (field_delimited*) malloc(sizeof (field_delimited) * number_of_fields);

         field_delimited * field_delimited_ptr = _field_delimited; 
        if (_field_delimited) {
            for (int i = 0; i < number_of_fields; i++) {
                (field_delimited_ptr + i)->name = (char *)  malloc(sizeof (char) * 256);
                (field_delimited_ptr + i)->data_type = (char *)  malloc(sizeof (char) * 256);
                (field_delimited_ptr + i)->description = (char *)  malloc(sizeof (char) * 256);
                (field_delimited_ptr + i)->unit = (char *)  malloc(sizeof (char) * 256);


            }
        } else {
            printf("malloc_field_delimited(), unable to allocate memory, exiting!");
            exit(1);
        }

        return _field_delimited;
    }

我也尝试使用memset()，但是它是无用的，同样的问题。

为什么get_data()中的char值丢失&我如何解决这个问题？

我想坚持通过char *使用动态分配的字符串，而不是使用字符串。

多谢百万！

Answer 1

_file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].name = XMLString::transcode(child->getTextContent());

您正在重写您的指针，丢失以前分配的内存。您应该使用strcpy代替。

    strcpy(_file_observational_area->_table_delimited->_record_delimited->_field_delimited[Record_Delimited_index ].name, XMLString::transcode(child->getTextContent()));