Text-adventure game cleanup

Question

I'm working on a text adventure game for a while now, learning more about user input etc. I have a feeling there is something fundamentally wrong about my code, it seems too repetitive.

The use of structs should make things less bulky but can't figure out how to use it properly.

#include <stdio.h>
#include <time.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

// FUNCTIONS
int readLine();
int execute();
void startUp();
void readLocation();
void executeOpen();
void executeOpenDoor();
void executeOpenFridge();
void executeReadSign();
void executeGo();

// LOCATIONS
struct location {
    const char *description;
    const char *name;
}
locs[] = {
    {""},
    {"hallway", "hall"},
    {"kitchen", "kitchen"},
    {"living room", "living room"},
    {"toilet", "toilet room"},
    {"upstairs", "first floor"},
};
void loc_kitchen();
void loc_living();
void loc_hall();
void loc_toilet();
void loc_upstairs();

// INIT
int answer, location;
int bullets, key, gun = 0;
char* current_loc = "hall";
static char input[100];

// MAIN GAME
int main()
{    
    startUp(); // INTRO

    while (readLine() && execute()); // GAME LOOP

    return 0;
}


// FUNCTIONS
// COMMAND & READLINE
int readLine ()
{
    printf(">  ");
    return fgets(input, sizeof(input), stdin) != NULL;
}

int execute()
{
    char *verb = strtok(input, " \n");
    char *noun = strtok(NULL, " \n");

    if (verb != NULL)
    {        
        if (strcasecmp(verb, "open") == 0) 
        {
            executeOpenDoor(noun);
        }
        else if (strcasecmp(verb, "read") == 0) 
        {
            executeReadSign(noun);
        }
        else 
            printf("I don't know the word %s, try again.\n\n", verb);
    }
    return 1;
}

void executeOpenDoor(const char *noun)
{
    if (noun == NULL)
    {
        printf("What do you want to open?\n\n");
    }
    else if (strcasecmp(noun, "door") == 0)
    {        
        printf("You enter the mansion, seems like nobody's been here in years..\n");
        printf("You now have access to the kitchen, toilet, living room & upstairs.\n\n");
        readLocation();
    }
    else
    {
        printf("I don't understand what you want to open.\n\n");
    }
}

void readLocation() 
{
    while (1)
    {
        readLine();

        char *verb = strtok(input, " \n");
        char *noun = strtok(NULL, " \n");

        if (strcasecmp(verb, "go") == 0)
        {
            executeGo(noun);
        }
        else
        {
            printf("I don't understand where you want to go.\n\n");
        }
    }
}

void executeOpenFridge(const char *noun)
{
    if (noun == NULL)
    {
        printf("What do you want to open?\n\n");
    }
    else if (strcasecmp(noun, "fridge") == 0)
    {        
        printf("Oh wish you didnt opened that. Whatever's in it, it's definitely out-of-date.\n\n");
    }
    else
    {
        printf("I don't know what you want to open.\n\n");
    }
}

void executeReadSign(const char *noun)
{
    if (noun == NULL)
    {
        printf("What do you want to read?\n\n");
    }
    else if (strcasecmp(noun, "sign") == 0)
    {
        printf("\"Begone, leave the dead in peace!\"\n\n");
    }
    else
    {
        printf("I don't know what you want to read.\n\n");
    }
}

void executeGo(const char *noun)
{    
    if (strcasecmp(noun, current_loc) == 0)
    {
        printf("You are already standing in the %s.\n\n", current_loc);
    }
    else if (noun == NULL)
    {
        printf("Where do you want to go?\n\n");
    }
    else if (strcasecmp(noun, "kitchen") == 0)
    {
        loc_kitchen();
    }
    else if (strcasecmp(noun, "toilet") == 0)
    {
        loc_toilet();
    }
    else if (strcasecmp(noun, "hall") == 0)
    {
        loc_hall();
    }
    else if (strcasecmp(noun, "living") == 0)
    {
        loc_living();
    }
    else if (strcasecmp(noun, "upstairs") == 0)
    {
        loc_upstairs();
    }
    else
    {
        printf("I don't know where you want to go.\n\n");
    }
}

void loc_hall()
{
    current_loc = "hall"; // ADD LOCATION
    printf("You have access to the kitchen, toilet, living room & upstairs.\n\n");

    while (1)
    {
        readLine();

        char *verb = strtok(input, " \n");
        char *noun = strtok(NULL, " \n");

        if (strcasecmp(verb, "go") == 0) 
        {
            executeGo(noun);
        } 
        else
        {
            printf("I don't know the word %s.\n\n", verb);
        }
    }
}

void loc_kitchen()
{
    current_loc = "kitchen"; // ADD LOCATION
    printf("There are several cupboards and drawers ajar, there's also a weird\n");
    printf("smell coming from the fridge.\n\n");

    while (1)
    {
        readLine();

        char *verb = strtok(input, " \n");
        char *noun = strtok(NULL, " \n");

        if (strcasecmp(verb, "search") == 0) 
        {
            if (gun == 1) {
                gun++;
                printf("You filled your shotgun with bullets.\n");
                printf("When you put the bullets in the gun, you hear a door being slammed shut upstairs.\n\n");
            }
            else if (gun == 2 || bullets == 1){
                printf("You already found ammo in the drawers.\n\n");
            }
            else 
            {
                printf("In one of the drawers you found some salt bullets. These might come in handy!\n\n");
                bullets++;
            }
        } 
        else if (strcasecmp(verb, "open") == 0) 
        {
            executeOpenFridge(noun);
        }
        else if (strcasecmp(verb, "go") == 0) 
        {
            executeGo(noun);
        } 
        else
        {
            printf("I don't know the word %s.\n\n", verb);
        }
    }
}

void loc_living()
{
    current_loc = "living"; // ADD LOCATION
    printf("The furniture is covered with white cloth, but the colour has become\n");
    printf("yellow out of age. The carpet has blood and dirt stains on it.\n");
    if (!gun)
    {
        printf("Above the fireplace you see a double-barreled shotgun.\n");
    }
    printf("\n");

    while (1)
    {
        readLine();

        char* verb = strtok(input, " \n");
        char* noun = strtok(NULL, " \n");

        if (strcasecmp(verb, "take") == 0) 
        {
            if (bullets) {
                gun = 2;
                printf("You got yourself a gun, you filled it up with the salt bullets you found in the kitchen.\n");
                printf("When you put the bullets in the gun, you hear a door being slammed shut upstairs.\n\n");
            }
            else if (gun > 0)
            {
                printf("You already have the gun.\n\n");
            }
            else 
            {
                gun++;
                printf("You took the gun, empty.. We need some find some bullets.\n\n");
            }
        }
        else if (strcasecmp(verb, "go") == 0) 
        {
            executeGo(noun);
        } 
        else
        {
            printf("I don't know the word %s.\n\n", verb);
        }
    }
}

void loc_toilet()
{
    current_loc = "toilet"; 
    printf("You sure have a small bladder, couldn't you go before we started playing?\n\n");
    readLocation();
}

void loc_upstairs()
{
    current_loc = "upstairs"; 
    if (gun != 2) {
        printf("Maybe we need to find something to defend ourself first.\n\n");
    }
    else
    {
        printf("There are 2 doors, which one do you want to take? Left or right?\n\n");
    }
}

void startUp()
{
    printf("You stand in front of the mansion, there is a sign on the door.\n\n");
}
```

Answer 1

Static functions

Given that this is a one-file program, all of your functions (except main) and global variables should be marked static as they will not be used in other translation units.

stdbool

Functions like readLine should return bool (from stdbool.h), and not int.

This will also allow

while (1)

to change to

while (true)

Global state

Most of your global variables after // INIT should be moved. input should just be a local variable. The others could be moved into a game state structure that gets passed around, to enable re-entrance.

Simple output

I prefer puts to printf when you are only outputting a string literal with no formatting. Note that puts includes a newline, so

printf("What do you want to open?\n\n");

would turn into

puts("What do you want to open?\n");

but printf("> "); would stay as-is.

The reasons I prefer this change:

• it produces more terse code;
• if we were to assume a non-optimizing compiler, printf would be slower; and
• puts is constrained to a much simpler set of behaviour.

executeGo

Rather than representing this as a long list of if statements, you could factor it out into an array of string/function-pointer pairs. Iterate through them until you find a matching string and call the appropriate function. If this list gets longer as you add to the game, consider using a dictionary library.

Answer 2

There are a few ways that struct types, and restructuring in general, could clean up your code.

Stack Overflow

First, I'll point out that your code is infinitely mutually recursive. If a player goes from the kitchen to the hall and back again, over and over, the stack will overflow.

As such, you should first concentrate on eliminating this recursion. Understand why you felt the need to encode it, and move that reason into some kind of data structure that is independent of the stack.

The three most important things in real estate:

Your various loc_ functions seem to have a similar structure. First they set a location string, then they mostly print a static message (with one exception), then they maybe print some extra text depending on the player's inventory or past actions.

Some of the locations then enter a nested command loop, but that should be addressed above.

So if you had a data structure that encoded those data items, you could process all the loc_ code with a single function. Something like:

typedef struct LOCATION {
    const char * name;
    const char * enter_msg;
    struct CONDITIONAL_MESSAGE {
        int    item_id;
        const char * per_item_msg;
    } * conditional_messages;
} LOCATION;

If your maze grows to require it, you might include a function pointer for really complex rooms. Also, you might want to have a "first time" entry message and a "every other time" entry message, so the game doesn't get too verbose.

Sic transit gloria mundi!

English verbs are divided between transitive and intransitive forms. Transitive verbs take an object while intransitive verbs do not.

An example of an intransitive verb would be "quit" -- the command you should always implement first. A transitive verb would be something like "go kitchen" or "read note".

Most of your verbs are transitive, which is fine. But the transitive verbs have a very similar structure when you process them:

1. Was there an object specified? If not, snark.
2. Is the object valid for this verb? If so, do something.
3. If not, snark.

So that leads to the suggestion that you move as much of this structure as possible into your parsing engine, and clean up the rest of your code.

struct VERB {
    unsigned flags;
    const char * word;
    const char * no_object_msg;
    const char * bogus_object_msg;
    // maybe a helper function?
};

Lots and lots of lists and lists

When thinking about transitive verbs, there are three obvious sources for objects. First, there is the map itself. The various "go XXX" commands will change based on where a player is standing. So it makes sense for there to be a list of rooms that is currently reachable.

The "take" verb, and the "open" verb, both suggest that there should be a list of items in the room. Some of those items are take-able, like the gun or the ammo. If taken, these items will leave the room and move into the player's inventory. Other items are permanently in the room, like a door or the fridge. You can still open them, but cannot have them in inventory. (A bit flag would be sensible for this. CAN_TAKE, CAN_OPEN, etc.)

Finally, there are the items in the player's inventory. These items will "always" be available, regardless of what room the player is in. You have used global variables for this, which IMO is a mistake. Better to create an array or a list.

Once you have all these lists figured out, you can search them for verb-objects. If the player enters, "take gun", it makes sense to check her inventory for the gun and print "you already have that", then check the room inventory for a gun that is take-able.

Hope this helps.