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--- start:prog2:lectures:code4 [2017/04/20 21:26]
kkv created
+++ start:prog2:lectures:code4 [2022/12/10 09:08] (current)
@@ Line 1: / Line 1: @@
 <code c++>
+// Programming 1. Sample at 2017-04-13-13-54.09
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+const size_t BUFFERSZ = 1000;
+int g_location_items = 0;
-</code c++>
+struct LocationIterator
+{
+  long   filepos;
+  char   location[20];
+  struct LocationIterator *next;
+};
+struct LocationIterator *locations = NULL;
+struct LocationIterator **nextLocationItem = &locations;
+// shifts <location> to the beginning of the buf
+void shift_buffer(char *buf, size_t size, size_t tailsz, FILE *file)
+{
+  memmove(buf,buf+size,(BUFFERSZ-1)-size);
+  int rsz = fread(buf+((BUFFERSZ-1)-size),1,size,file);
+  buf[rsz]=0;
+}
+void extractLocation(const char *src, char *dest)
+{
+  memset(dest,0,20);
+  const char * endTag = strstr(src,"<");
+  if(NULL == endTag || (endTag - src)>19)
+    strncpy(dest,src,19);
+  else
+    strncpy(dest,src,endTag-src);
+}
+// add new LocationItem
+void addLocation(const char *tag, FILE *file)
+{
+  const char *locationValue = tag+strlen("<location>");
+  *nextLocationItem =
+        (struct LocationIterator*)malloc(sizeof(struct LocationIterator));
+  (*nextLocationItem)->filepos = ftell(file)-(BUFFERSZ-1);
+  extractLocation(locationValue,(*nextLocationItem)->location);
+  printf("%d: Location: [%s] \n",g_location_items++, (*nextLocationItem)->location);
+  *nextLocationItem=(*nextLocationItem)->next;
+}
+// Search the next <location> tag
+void find_all_locations(FILE *file, char *buf)
+{
+  char *startTag = NULL;
+  char *locationPtr = NULL;
+  do
+  {
+    size_t rd = fread(buf, 1, BUFFERSZ-1, file);
+    if(rd <= 1)
+      break;
+    startTag=strchr(buf,'<');
+    // read the next buffer, there's no <
+    if( NULL == startTag)
+      continue;
+    shift_buffer(buf, startTag-buf, startTag-buf, file);
+    locationPtr = strstr(buf, "<location>");
+    if(buf == locationPtr)
+      addLocation(buf,file);
+  } while(!feof(file));
+}
+void initLocations(const char *filename)
+{
+  char buf[BUFFERSZ];
+  FILE *file = fopen(filename,"r");
+   printf("file = %p\n",file);
+  if(NULL == file)
+    return;
+  memset(buf,0,BUFFERSZ);
+  find_all_locations(file, buf);
+  fclose(file);
+}
+int main(/*int c, char **v */)
+{
+  initLocations("./database");
+  return 0;
+}
+</code>

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