/* This is simple demonstration of how to use expat. This programreads an XML document from standard input and writes a line with thename of each element to standard output indenting child elements byone tab stop more than their parent element. */#include <stdio.h>#include "xmlparse.h"void handleElementData(void *userData, const char * data, int len) {  int i;  int *depthPtr = userData;  if (len < 3) return;  for (i = 0; i < *depthPtr; i++)    putchar('\t');  printf("    tag data: ");  for (i=0; i<len; i++) {    putchar(data[i]);  }  printf("\n");}void startElement(void *userData, const char *name, const char **atts){  int i;  int *depthPtr = userData;  for (i = 0; i < *depthPtr; i++)    putchar('\t');  printf("tag name: ");  puts(name);  *depthPtr += 1;}void endElement(void *userData, const char *name){  int *depthPtr = userData;  *depthPtr -= 1;}int main(){  char buf[BUFSIZ];  XML_Parser parser = XML_ParserCreate(NULL);  int done;  int depth = 0;  XML_SetUserData(parser, &depth);  XML_SetElementHandler(parser, startElement, endElement);  XML_SetCharacterDataHandler(parser, handleElementData);  do {    size_t len = fread(buf, 1, sizeof(buf), stdin);    done = len < sizeof(buf);    if (!XML_Parse(parser, buf, len, done)) {      fprintf(stderr,	      "%s at line %d\n",	      XML_ErrorString(XML_GetErrorCode(parser)),	      XML_GetCurrentLineNumber(parser));      return 1;    }  } while (!done);  XML_ParserFree(parser);  return 0;}