Question 135723 in Visual Studio Code Question posted in
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Visual Studio Code – Why am I getting an "undefined reference to `parseAndExecute' " error here?

I’m using an online tutorial on how to make a Text Adventure game (in VSC) and came across a really annoying issue. Even after copying all the source code from the tutorial, I receive an ‘undefined reference’ error. I tried editing the ‘tasks.json’ file as described here: undefined reference error in VScode
but with no success.

The game consists of multiple c files in order to work, the source code is at the bottom of the page here: https://helderman.github.io/htpataic/htpataic05.html

Here’s all the files, Thanks a lot in advance for any help!

    <main.c>

#include <stdbool.h>
#include <stdio.h>
#include "parsexec.h"


static char input[100] = "look around";

static bool getInput(void)
{
   printf("n--> ");
   return fgets(input, sizeof input, stdin) != NULL;
}

int main()
{
   printf("Welcome to Little Cave Adventure.n");
   while (parseAndExecute(input) && getInput());
   printf("nBye!n");
   return 0;
}

<parsexec.h>

   

 extern bool parseAndExecute(char *input);

    <parsexec.c>

#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include "location.h"
#include "inventory.h"

bool parseAndExecute(char *input)
{
   char *verb = strtok(input, " n");
   char *noun = strtok(NULL, " n");
   if (verb != NULL)
   {
      if (strcmp(verb, "quit") == 0)
      {
         return false;
      }
      else if (strcmp(verb, "look") == 0)
      {
         executeLook(noun);
      }
      else if (strcmp(verb, "go") == 0)
      {
         executeGo(noun);
      }
      else if (strcmp(verb, "get") == 0)
      {
         executeGet(noun);
      }
      else if (strcmp(verb, "drop") == 0)
      {
         executeDrop(noun);
      }
      else if (strcmp(verb, "give") == 0)
      {
         executeGive(noun);
      }
      else if (strcmp(verb, "ask") == 0)
      {
         executeAsk(noun);
      }
      else if (strcmp(verb, "inventory") == 0)
      {
         executeInventory();
      }
      else
      {
         printf("I don't know how to '%s'.n", verb);
      }
   }
   return true;
}

<location.c>

#include <stdio.h>
#include <string.h>
#include "object.h"
#include "misc.h"
#include "noun.h"

void executeLook(const char *noun)
{
   if (noun != NULL && strcmp(noun, "around") == 0)
   {
      printf("You are in %s.n", player->location->description);
      listObjectsAtLocation(player->location);
   }
   else
   {
      printf("I don't understand what you want to see.n");
   }
}

void executeGo(const char *noun)
{
   OBJECT *obj = getVisible("where you want to go", noun);
   if (obj == NULL)
   {
      // already handled by getVisible
   }
   else if (obj->location == NULL && obj != player->location)
   {
      printf("OK.n");
      player->location = obj;
      executeLook("around");
   }
   else
   {
      printf("You can't get much closer than this.n");
   }
}

  <location.h>
    extern void executeLook(const char *noun);
    extern void executeGo(const char *noun);

<object.c>
#include <stdio.h>
#include "object.h"

OBJECT objs[] = {
   {"an open field", "field"   , NULL  },
   {"a little cave", "cave"    , NULL  },
   {"a silver coin", "silver"  , field },
   {"a gold coin"  , "gold"    , cave  },
   {"a burly guard", "guard"   , field },
   {"yourself"     , "yourself", field }
};

<object.h>
typedef struct object {
   const char    *description;
   const char    *tag;
   struct object *location;
} OBJECT;

extern OBJECT objs[];

#define field      (objs + 0)
#define cave       (objs + 1)
#define silver     (objs + 2)
#define gold       (objs + 3)
#define guard      (objs + 4)
#define player     (objs + 5)

#define endOfObjs  (objs + 6)

<noun.c>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include "object.h"

static bool objectHasTag(OBJECT *obj, const char *noun)
{
   return noun != NULL && *noun != '' && strcmp(noun, obj->tag) == 0;
}

static OBJECT *getObject(const char *noun)
{
   OBJECT *obj, *res = NULL;
   for (obj = objs; obj < endOfObjs; obj++)
   {
      if (objectHasTag(obj, noun))
      {
         res = obj;
      }
   }
   return res;
}

OBJECT *getVisible(const char *intention, const char *noun)
{
   OBJECT *obj = getObject(noun);
   if (obj == NULL)
   {
      printf("I don't understand %s.n", intention);
   }
   else if (!(obj == player ||
              obj == player->location ||
              obj->location == player ||
              obj->location == player->location ||
              obj->location == NULL ||
              obj->location->location == player ||
              obj->location->location == player->location))
   {
      printf("You don't see any %s here.n", noun);
      obj = NULL;
   }
   return obj;
}

OBJECT *getPossession(OBJECT *from, const char *verb, const char *noun)
{
   OBJECT *obj = NULL;
   if (from == NULL)
   {
      printf("I don't understand who you want to %s.n", verb);
   }
   else if ((obj = getObject(noun)) == NULL)
   {
      printf("I don't understand what you want to %s.n", verb);
   }
   else if (obj == from)
   {
      printf("You should not be doing that to %s.n", obj->description);
      obj = NULL;
   }
   else if (obj->location != from)
   {
      if (from == player)
      {
         printf("You are not holding any %s.n", noun);
      }
      else
      {
         printf("There appears to be no %s you can get from %s.n",
                noun, from->description);
      }
      obj = NULL;
   }
   return obj;
}

<noun.h>
extern OBJECT *getVisible(const char *intention, const char *noun);
extern OBJECT *getPossession(OBJECT *from, const char *verb, const char *noun);

<inventory.c>
#include <stdio.h>
#include "object.h"
#include "misc.h"
#include "noun.h"
#include "move.h"

void executeGet(const char *noun)
{
   OBJECT *obj = getVisible("what you want to get", noun);
   if (obj == NULL)
   {
      // already handled by getVisible
   }
   else if (obj == player)
   {
      printf("You should not be doing that to yourself.n");
   }
   else if (obj->location == player)
   {
      printf("You already have %s.n", obj->description);
   }
   else if (obj->location == guard)
   {
      printf("You should ask %s nicely.n", obj->location->description);
   }
   else
   {
      moveObject(obj, player);
   }
}

void executeDrop(const char *noun)
{
   moveObject(getPossession(player, "drop", noun), player->location);
}

void executeAsk(const char *noun)
{
   moveObject(getPossession(actorHere(), "ask", noun), player);
}

void executeGive(const char *noun)
{
   moveObject(getPossession(player, "give", noun), actorHere());
}

void executeInventory(void)
{
   if (listObjectsAtLocation(player) == 0)
   {
      printf("You are empty-handed.n");
   }
}

<inventory.h>
extern void executeGet(const char *noun);
extern void executeDrop(const char *noun);
extern void executeAsk(const char *noun);
extern void executeGive(const char *noun);
extern void executeInventory(void);

<misc.c>
#include <stdio.h>
#include "object.h"

OBJECT *actorHere(void)
{
   OBJECT *obj;
   for (obj = objs; obj < endOfObjs; obj++)
   {
      if (obj->location == player->location && obj == guard)
      {
         return obj;
      }
   }
   return NULL;
}

int listObjectsAtLocation(OBJECT *location)
{
   int count = 0;
   OBJECT *obj;
   for (obj = objs; obj < endOfObjs; obj++)
   {
      if (obj != player && obj->location == location)
      {
         if (count++ == 0)
         {
            printf("You see:n");
         }
         printf("%sn", obj->description);
      }
   }
   return count;
}

<misc.h>

    extern OBJECT *actorHere(void);
    extern int listObjectsAtLocation(OBJECT *location);

<move.c>
#include <stdio.h>
#include "object.h"

static void describeMove(OBJECT *obj, OBJECT *to)
{
   if (to == player->location)
   {
      printf("You drop %s.n", obj->description);
   }
   else if (to != player)
   {
      printf(to == guard ? "You give %s to %s.n" : "You put %s in %s.n",
             obj->description, to->description);
   }
   else if (obj->location == player->location)
   {
      printf("You pick up %s.n", obj->description);
   }
   else
   {
      printf("You get %s from %s.n",
             obj->description, obj->location->description);
   }
}

void moveObject(OBJECT *obj, OBJECT *to)
{
   if (obj == NULL)
   {
      // already handled by getVisible or getPossession
   }
   else if (to == NULL)
   {
      printf("There is nobody here to give that to.n");
   }
   else if (obj->location == NULL)
   {
      printf("That is way too heavy.n");
   }
   else
   {
      describeMove(obj, to);
      obj->location = to;
   }
}

<move.h>
extern void moveObject(OBJECT *obj, OBJECT *to);

Image of the issue in VSC:
https://i.stack.imgur.com/5mkzV.png

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    It turned out to be a faulty compiler/settings in VSC as the code ran fine on a different machine.


  2. 0

    Your code doesn’t compile as it relies on header files you haven’t shared with us, and executeAsk() for which we have no implementation. I removed the missing bits from parsexec.c:

    #include <stdbool.h>
#include <stdio.h>
#include <string.h>

bool parseAndExecute(char *input) {
    char *verb = strtok(input, " n");
    char *noun = strtok(NULL, " n");
    if (verb != NULL) {
        printf("I don't know how to '%s'.n", verb);
    }
    return true;
}

    and was then able to build and execute your game:

    gcc main.c parsexec.c -o game && ./game
Welcome to Little Cave Adventure.
I don't know how to 'look'.

--> look
I don't know how to 'look'.

--> ^C

    This tells me it’s a build issue. Specifically, you are probably not linking parsexec.o to your binary.

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