adding source and executable

db.c

@@ -0,0 +1,326 @@
+/*
+lookup value (key, value)
+add pair (key, value)
+change value (key, value)
+remove pair (key)
+*/
+
+#include "db.h"
+
+//--------------------------------------------------
+//
+//  GET VALUE FROM GENERAL DATABASE
+//
+//  inputs
+//    key, value
+//
+//  returns
+//  FOUND or NOT_FOUND
+//
+//  1) opens the database
+//  2) gets a line
+//  3) extracts the key
+//  4) checks the key to see if it's the one we're looking for
+//  5) goes to step 2 if not
+//  6) returns value
+//
+int db_lookup(char*target_key, char*db_value){
+
+    FILE *general;
+    int linepos;
+    char *status;
+    char line[80];
+    char db_key[60];
+
+   //  open general knowlege database
+    general = fopen("general.txt","r");
+    if(general == NULL) return CANT_OPEN_FILE;
+
+    // search for key
+    while(1){
+	   // get a line
+	   status = fgets(line,80,general);
+       if (status==0){
+    	  fclose(general);
+          return NOT_FOUND;
+       }
+
+     // get the key
+       linepos =  copy_to_delimiter(line, db_key, ':', 0);
+       // is it the key we're looking for?
+       // if not, get another line
+
+       if(strcmp(target_key, db_key) != 0) continue;
+       break;
+	} // end of key search
+
+    // get value
+    db_copy_word(line, linepos, db_value);
+
+    fclose(general);
+
+    return FOUND;  // (found)
+
+}
+
+
+//-------------------------------------------------------------------
+//
+//   example:  db_add_pair("grass > color","green");
+//
+//
+int db_add_pair(char*key, char*value){
+
+    FILE *general;
+
+   //open
+	  general = fopen("general.txt","a");
+	  if(general == NULL) {printf("fopen failed while trying to open general.txt");}
+
+   //add key and value
+	  fprintf(general, "%s:%s\n", key, value);
+
+   // close
+	  fclose(general);
+
+	  return 1;
+
+}
+
+
+//--------------------------------
+//    look up a first name and return the id number
+//    returns 0 if error
+//
+//
+int db_get_id(char* firstname)
+{
+
+    int id;
+    char id_string[20], name[20];
+    char key[80];
+    int result;
+
+    for(id=1; id<1000; id++)
+    {
+        itoa(id, id_string,10);  // convert id number from integer to string (integer, string, base)
+        sprintf(key, "#%s > firstname", id_string);
+        result = db_lookup(key, name);
+
+        // look up the first name
+        if(result==FOUND)
+        {
+            result = strcmp(name, firstname);
+            if(result==0)
+            {
+                // That's the entity we're looking for
+                return id;
+            }
+            // That's not the entity we're looking for, so try again
+            else {
+                continue;
+            }
+        }
+    }
+
+    return 0; // database size limit reached (DGI)
+
+}
+
+
+//--------------------------------------------------------
+//
+// looks for the specified key and changes its value
+//
+//
+
+int db_change_value(char*key, char*value){
+    FILE *general;
+    FILE *temp;
+
+    char *status;
+    char line[80];
+    char db_key[60];
+
+    //open files
+   	general = fopen("general.txt","r");
+	   if(general == NULL) {
+       printf("DB: can't open general.txt");
+       return 2;
+    }
+	temp = fopen("temp.txt","w");
+   	if(temp == NULL) {
+       printf("DB: can't open temp.txt");
+       fclose(general);
+       return 2;
+    }
+
+    // search for a key, copy each line
+    while(1){
+	      // get a line
+	      status = fgets(line,80,general);
+       if (status==0){
+          fclose(general);
+          fclose(temp);
+          return 1;  //(key not found)
+	      }
+
+       db_copy_word(line,1, db_key);
+       // is it the key we're looking for?
+       // if not, get another line
+       if(strcmp(key, db_key)==0) {
+         fprintf(temp, "%s", line); // copy line to temp file
+         break;
+       }
+    }  // end of subject search
+
+    //add key and value
+	   fprintf(temp, "%s: %s\n", key, value);
+
+
+    // copy remainder of file
+    //   fprintf(temp, "%s", line); // copy line to temp file
+    while(1){
+        // get another line
+		     status = fgets(line,80,general);
+		     if (status==0) break;
+ 	        fprintf(temp, "%s", line); // copy line to temp file
+       }
+
+    // close
+	   fclose(general);
+	   fclose(temp);
+
+   	if(remove("general.txt") != 0) {printf("oops, file error ""%s"" \n", strerror(1));}
+	   if(rename("temp.txt","general.txt") != 0) {printf("file error ""%s"" \n", strerror(1));}
+
+	   return 0;  // (success)
+
+}
+
+
+
+
+
+//--------------------------------------------------------
+
+int db_next_available_id(void){
+
+   int i;
+   char value[20];
+   int result;
+   char key[20], id_string[20];
+
+   //id[0]=0;
+   for(i=1; i<1000; i++){
+      // look for id, first_name
+      itoa(i,id_string,10);
+      strcpy(key,"#");
+      strcat(key, id_string);
+      strcat(key, " > class");
+      result = db_lookup(key,value);
+      if(result != FOUND){
+        //    printf("%d, %s   ", i, id_string);
+         return i;
+      }
+   }
+
+   printf("error in function DNAI");
+    return 0;
+}
+
+//----------------------------------------------------------
+//
+//
+//
+//
+//
+int db_copy_word(char* line, int position, char* value)
+{
+
+    int i;
+
+    for(i=0; i<MAX_LETTERS-2; i++)
+    {
+        //skip over leading spaces and tabs
+        if(line[position]==' ') position++;
+        if(line[position]==' ') position++;
+        if(line[position]==' ') position++;
+        if(line[position]=='\t') position++;
+        if(line[position]=='\t') position++;
+        if(line[position]=='\t') position++;
+
+        if ((isalpha(line[position])==0) && (isdigit(line[position])==0))
+        {
+            value[i]=0;
+
+            return position;
+        }
+        else
+        {
+            value[i]=line[position];
+            position++;
+        }
+    }
+
+    return position;
+
+}
+
+//------------------------------
+//
+// COPIES A STRING UP TO THE DELIMITER
+//
+// parameters: from, to
+//
+// returns: the position after the delimiter
+//
+// usualy the copy then gets compared to a key that's being searched for
+//
+int copy_to_delimiter(char* from, char* to, char delimiter, int start){
+
+   int i;
+
+   for(i=0; i<80; i++){
+      if (from[i+start] == delimiter){
+         to[i] = NULL; //
+         return i + 1 + start;
+      }
+      else if (from[i+start] == 10 || from[i+start] == 13){
+         to[i] = NULL; //
+         return 0;
+      }
+      else{
+         to[i] = from[i+start];
+      }
+   }
+   i++;
+   to[i+start] = NULL;
+return i;
+}
+
+
+//-----------------------------------------------------------------------
+//
+// ex: is cat a creature?
+// db_root_check("cat", "creature");
+//
+int db_root_check(char* startingwith, char* lookingfor){
+                      //  animal              creature
+   int result;
+   int n;
+   char subject[60];
+   char key[60];
+   char value[20];
+
+   strcpy(subject, startingwith);
+   for(n=0; n<5; n++){
+       sprintf(key, "%s > class", subject);
+       result = db_lookup(key, value); // lookup
+       if(result == NOT_FOUND) return NOT_FOUND; // if not in database at all, exit
+       if(strcmp(value,lookingfor)==0)return MATCH;  // is it what we're looking for?
+       if(strcmp(value,"root")==0)return NO_MATCH; // has it reached to root?
+       strcpy(subject,value); // if no luck so far, the value becomes the subject
+   }
+  return NO_MATCH;  // not found
+}

db.h

@@ -0,0 +1,33 @@
+#ifndef DB_H_INCLUDED
+#define DB_H_INCLUDED
+
+#define NOT_FOUND   0
+#define FOUND       1
+#define MATCH       2
+#define NO_MATCH    3
+#define EOF         4
+#define CANT_OPEN_FILE 5
+#define MAX_WORDS 40
+#define MAX_LETTERS 20
+
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdlib.h>
+
+// ENUM TEST
+enum{
+A1,
+B1,
+C1,
+};
+
+int db_lookup(char*,char*);
+int db_root_check(char*,char*);
+int db_next_available_id(void);
+int db_get_id(char*);
+int db_copy_word(char*, int, char*); // copies string up to a space
+int copy_to_delimiter(char*, char*, char, int); // copies string up to a delimiter
+int db_add_pair(char*, char*);
+
+#endif // DB_H_INCLUDED