Thread: pointer/array/struct problem

Try

Code:

printf("%d",*p_map);

>printf("%d",*p_map[player.x][player.y]);
The subscript operator dereferences for you, so unless the elements of map are pointers, this is one indirection too much. Actually, it's two indirections too much because p_map is a pointer, not a pointer to a pointer or a pointer to an array. In this case you're pretty much stuck with calculating the dimensions yourself unless you want to change the declaration of p_map:

Code:

#define sz(arr) sizeof arr / sizeof arr[0]
printf("%d\n",p_map[player.x * sz(map[0]) + player.y]);

If you show us exactly what you're trying to do then we can suggest some solutions.

well here is the entire code i got now. its very rough, but i finally got it working last night.

Code:

#include <stdio.h>
#include <stdlib.h>
#define WALL 1
#define NOWALL 0
#define MAXMAP 9
#define MINMAP 0

bool NORTH = true;
bool SOUTH = true;
bool EAST = true;
bool WEST = true;

struct object
{
    int x;
    int y;
    char name[15];

};
struct object player = {1,1};

void init();

void check();
void move(char *);

int map[10][10] =
                  {1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 ,
                   1 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 1 ,
                   1 , 0 , 1 , 1 , 1 , 0 , 1 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 1 , 1 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 0 , 0 , 0 , 0 , 1 , 1 , 0 , 1 ,
                   1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 };

int main()
{

    init();
    char dir = '\0';
    do
    {
        scanf(" %c",&dir);
        system("cls");
        move(&dir);
        check();
    }while(dir != 'q');

    return 0;
}

void init()
{
    //pre-processing
    printf("Enter you character's name \n");
    scanf(" %s",player.name);
    system("cls");
    printf("Welcome %s\n\n",player.name);

    check();
}

void move(char *p_dir)
{
    //select direction
    switch(*p_dir)
    {
        case 'n':
            if (NORTH == true) player.x--;
            else printf("There is a wall in the way\n\n");
            break;


        case 's':
            if (SOUTH == true) player.x++;
            else printf("There is a wall in the way\n\n");
            break;


        case 'e':
            if (EAST == true) player.y++;
            else printf("There is a wall in the way\n\n");
            break;


        case 'w':
            if (WEST == true) player.y--;
            else printf("There is a wall in the way\n\n");
            break;

        case 'q':
            return;
    }
}

void check()
{
    //check exits
    printf("Player is at %d, %d\n\n",player.x, player.y );
    if (map[player.x-1][player.y] == WALL) NORTH = false;
    else NORTH = true;

    if (map[player.x+1][player.y] == WALL) SOUTH = false;
    else SOUTH = true;

    if (map[player.x][player.y+1] == WALL) EAST = false;
    else EAST = true;

    if (map[player.x][player.y-1] == WALL) WEST = false;
    else WEST = true;

    //print exits
    printf("Exits are \n\n");
    if (NORTH == true) printf("(N)orth ");
    if (SOUTH == true) printf("(S)outh ");
    if (EAST == true) printf("(E)ast ");
    if (WEST == true) printf("(W)est ");

    printf("\n(Q)uit\n");
}

1. i know bool is c++ (ill change it when i can be bothered)
2. system("cls") works for me
3. you mean i should have void check(void) ?
4. why would i not use the & operator? im passing the address to a pointer.
5. i told you it was rough.
6. thanks for the suggestions

>1. i know bool is c++ (ill change it when i can be bothered)
Add this:

Code:

typedef enum { false, true } bool;

And your code will still run when compiled as C. But it strikes me that you're compiling as C++. This can be dangerous because there are subtle differences between C and C++ that would cause you trouble.

>2. system("cls") works for me
That's fine, just be aware that your code is not portable to systems that don't support the cls command and will behave differently for systems that use cls for something other than clearing the screen.

>3. you mean i should have void check(void) ?
Yes. In C++ an empty argument list in a function prototype says that the function takes no arguments. In C an empty parameter list is a throwback to K&R C where it says the function takes an unknown number and type of arguments. It's generally a bad idea to mix old and new function declarations and definitions, so you should always use void to signify no arguments in your declarations.

>4. why would i not use the & operator? im passing the address to a pointer.
There's no need to pass a pointer when all you're doing is passing a single character. It's not a string, so a pointer to char is not required, and char is very likely smaller than pointer to char, so you're actually introducing inefficiency as well as obfuscating the code with needless indirection.

>init();
>char dir = '\0';
This won't work in C unless you use a compiler that supports C99. Because there aren't many people that do, we assume C89/90 here, and C89/90 requires that all declarations be placed at the beginning of a block, before any processing statements.

>But it strikes me that you're compiling as C++.
im a stupid n00b

thanks for the tips prelude.
so what is an alternative to system("cls") ?

Code:

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>


#define DEPTH 2
#define WALL 1
#define NOWALL 0
#define MAXFLOOR 2

typedef enum { false, true } bool;

bool NORTH = true;
bool SOUTH = true;
bool EAST = true;
bool WEST = true;
bool STAIRS = false;

struct object
{
    int x;
    int y;
    int z;
    int gold;
    int hp;
    char name[15];
};
struct object player = {1,1,0,300,50};

void init(void);           // pre-processing
void process(void);        // controls game loop

void check(void);          // checks available directions
void move(char *);         // moves player
void panel(void);

int map[3][10][10] =
                  {1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , // Floor 1 (0)
                   1 , 0 , 2 , 0 , 0 , 0 , 0 , 0 , 0 , 1 ,
                   1 , 0 , 1 , 1 , 1 , 0 , 1 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 1 , 1 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 0 , 0 , 0 , 0 , 1 , 1 , 0 , 1 ,
                   1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 ,

                   1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , // Floor 2 (1)
                   1 , 0 , 2 , 0 , 0 , 0 , 0 , 0 , 0 , 1 ,
                   1 , 0 , 1 , 1 , 1 , 0 , 1 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 1 , 1 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 0 , 0 , 0 , 0 , 1 , 1 , 0 , 1 ,
                   1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 ,

                   1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , // Floor 3 (2)
                   1 , 0 , 2 , 0 , 0 , 0 , 0 , 0 , 0 , 1 ,
                   1 , 0 , 1 , 1 , 1 , 0 , 1 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 1 , 1 , 1 , 0 , 0 , 1 , 0 , 1 ,
                   1 , 0 , 0 , 0 , 0 , 0 , 1 , 1 , 0 , 1 ,
                   1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 };

int main(void)
{
    init();
    process();
    return 0;
}

void init(void)
{

    printf("Enter you character's name \n");
    scanf(" %s",player.name);
    system("cls");
    printf("Welcome %s\n\n",player.name);

    check();
}

void process()
{
    char dir = '\0';
    do
    {
        panel();
        scanf(" %c",dir);
        system("cls");
        move(&dir);
        check();
    }while(dir != 'q');
}

void move(char *p_dir)
{
    //select direction
    switch(*p_dir)
    {
            // Processing for direction
        case 'n':
            if (NORTH == true) player.x--;
            else printf("There is a wall in the way\n\n");
            break;

        case 's':
            if (SOUTH == true) player.x++;
            else printf("There is a wall in the way\n\n");
            break;

        case 'e':
            if (EAST == true) player.y++;
            else printf("There is a wall in the way\n\n");
            break;

        case 'w':
            if (WEST == true) player.y--;
            else printf("There is a wall in the way\n\n");
            break;


            // Processing for STAIRS
        case 'u':
            if (STAIRS == true)
            {
                if (player.z != MAXFLOOR) player.z++;
                else printf("You cant go up here\n\n");
            }
            break;

        case 'd':
            if (STAIRS == true)
            {
                if (player.z != 0) player.z--;
                else printf("You cant go down here here\n\n");
            }
            else printf("You cant go down here here\n\n");
            break;

        case 'q':
            return;
    }
}

void check(void)
{
    //check exits
    printf("Player is at %d, %d on floor %d\n\n\n",player.x, player.y, player.z );
    if (map[player.z][player.x-1][player.y] == WALL) NORTH = false;
    else NORTH = true;

    if (map[player.z][player.x+1][player.y] == WALL) SOUTH = false;
    else SOUTH = true;

    if (map[player.z][player.x][player.y+1] == WALL) EAST = false;
    else EAST = true;

    if (map[player.z][player.x][player.y-1] == WALL) WEST = false;
    else WEST = true;

    if (map[player.z][player.x][player.y] == DEPTH) STAIRS = true;
    else STAIRS = false;
}

void panel()
{
    //print exits
    printf("Exits are \n");
    if (NORTH == true) printf("(N)orth ");
    if (SOUTH == true) printf("(S)outh ");
    if (EAST == true) printf("(E)ast ");
    if (WEST == true) printf("(W)est ");

    //print if STAIRS
    if (STAIRS == true && player.z < MAXFLOOR) printf("(U)p ");
    if (STAIRS == true && player.z > 0) printf("(D)own ");

    printf("\n(Q)uit\n\n");

    textcolor(DARKGRAY);
    cprintf("%s's Stats ",player.name);
    textcolor(WHITE);
    cprintf("HP: ");
    textcolor(RED);
    cprintf("%d ",player.hp);
    textcolor(WHITE);
    cprintf("GOLD: ");
    textcolor(YELLOW);
    cprintf("%d ", player.gold);

}

>so what is an alternative to system("cls") ?
There isn't a good solution to the clearing-the-screen problem. I usually recommend that you either think long and hard about why you want to clear the screen, or isolate the non-portable parts:

Code:

void
clear_screen(void)
{
  system("cls");
}

By only using clear_screen to clear the screen, you only have to make minor changes when porting the program. It won't run everywhere unchanged, but when it comes to useful and nontrivial programs, you have to loosen your definition of "portable" a bit.

You can find various ways to clear the screen in the FAQ.