The outcome of this function is heavily dependent on the parser implementation used. For example, at the point where the start_element_ callback is called, libxml2 parser consumes the entire element name and attributes, however expat does not.
(PHP 4, PHP 5, PHP 7, PHP 8)
xml_get_current_byte_index — 获取 XML 解析器的当前字节索引
parser指向要取得字节索引的 XML 解析器的引用。
返回解析器当前在其数据缓冲区中的字节索引（起始值为 0）。
该函数将返回根据 UTF-8 编码的文本的字节索引，而不论输入是否是其他的编码。
The outcome of this function is heavily dependent on the parser implementation used. For example, at the point where the start_element_ callback is called, libxml2 parser consumes the entire element name and attributes, however expat does not.