C++ 连接xmlChar*字符串

我正在尝试扭曲xmlChar*字符串，以便将“.rels”附加到文件名上。出于某种原因，我看到了错误：

错误c2440初始化无法从常量字符[6]转换为常量xmlChar*

const_cast只能调整类型限定符；它无法更改基础类型

xmlChar是从xmlstring.h libopc/libxml2定义的，因为我知道并不是每个人都知道xmlChar

xmlChar * temp = c->part_array[i].name; //this is a filename.doc with  path, has no compile error
                const xmlChar* temp2 = const_cast<xmlChar*>(".rels"); //"rels" here has error
                xmlStrcat(temp, temp2);

但是得到错误：

错误c2440初始化无法从常量字符[6]转换为常量字符 xmlChar*

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我最终不得不使用xmlStrndup和xmlCharStrndup

        xmlChar * temp = xmlStrndup(c->part_array[i].name, max_part_name);
        const char* tempA = ".rels";
        xmlChar* temp2 = xmlCharStrndup(tempA, sizeof(tempA));
        xmlStrcat(temp, temp2);
        const xmlChar* temp3 = (const xmlChar*)temp;

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直接铸造为我工作：

        xmlChar * temp = xmlStrndup(c->part_array[i].name, max_part_name);
        const char* tempA = ".rels";
        xmlChar* temp2 = xmlCharStrndup(tempA, sizeof(tempA));
        xmlStrcat(temp, temp2);
        const xmlChar* temp3 = (const xmlChar*)temp;