c++ allegro input

Question

I'm building a simple ice sliding puzzle to test uses of allegro. So far I've got the whole thing working although I haven't actually added in the objective yet or the puzzle, just the engine behind it. I'm having a little trouble making "r" jump the player back to the starting spot, can anyone tell me why?

#include <allegro.h>
#include "maps.cpp"

BITMAP* buffer;

int x = 15;
int y = 11;

int tempX = 15;
int tempY = 11;

int startX = 15;
int startY = 11;

//This will be our background, 1 = clouds, 2 = brick, 3 = floor
int map[24][32] = //{{2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,2,2,2,2,2,3,2,2,2,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,2,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,2},
                   //{2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2}};

//This will contain all the objects, 100 = player
int objMap[24][32] = //{{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
                   //{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}};

void setupGame(){

     buffer = create_bitmap( 640, 480);

    for (int i = 0; i <= 24; i++){

        for( int t = 0; t <= 32; t++){

            if( map[i][t] == 1) rectfill( buffer, t * 20, i * 20, (t + 1) * 20, (i + 1) * 20, makecol( 128, 255, 255));
            else if( map[i][t] == 2) rectfill( buffer, t * 20, i * 20, (t + 1) * 20, (i + 1) * 20, makecol( 255, 128, 0));
            else if( map[i][t] == 3) rectfill( buffer, t * 20, i * 20, (t + 1) * 20, (i + 1) * 20, makecol( 0, 0, 255));

           }       

    }

    for (int i = 0; i <= 24; i++){

        for( int t = 0; t <= 32; t++){

            if( objMap[i][t] == 100) circlefill( buffer, (t * 20) + 10, (i * 20) + 10, 10, makecol( 255, 255, 0));

           }       

    }

    draw_sprite( screen, buffer, 0, 0);

}

void movePlayer(){

    tempX = x;
    tempY = y;

    if(key[KEY_UP] && map[y - 1][x] == 3)
        for ( ; map[y - 1][x] == 3; --y){              
        }

    else if(key[KEY_DOWN] && map[y + 1][x] == 3)
        for ( ; map[y + 1][x] == 3; ++y){
        }

    else if(key[KEY_RIGHT] && map[y][x + 1] == 3)
        for ( ; map[y][x + 1] == 3; ++x){
        }

    else if(key[KEY_LEFT] && map[y][x - 1] == 3)
        for ( ; map[y][x - 1] == 3; --x){
        }
    else if(key[KEY_R] && map[startY][startX] == 3)
         for ( ; map[startY][startX] == 3 ; y = startY, x = startX){ // this is the section
         }


     acquire_screen();

     rectfill( buffer, tempX * 20, tempY * 20, (tempX + 1) * 20, (tempY + 1) * 20, makecol( 0, 0, 255));

     circlefill( buffer, (x * 20) + 10, (y * 20) + 10, 10, makecol( 255, 255, 0));

     draw_sprite( screen, buffer, 0, 0);
     release_screen();

     rest(20);
}

int main(){

    allegro_init();
    install_keyboard();
    set_color_depth(16);
    set_gfx_mode( GFX_AUTODETECT, 640, 480, 0, 0);

    setupGame();

    while( !key[KEY_ESC]){

           movePlayer();

    }

    return 0;

}

END_OF_MAIN();

it all runs except that section which it seems to skip.

If you can help, thanks

Answer 1

The for statement checks its finish condition (the middle section) before it ever carries out the statements in the last section. Since your finish condition is true before you enter the for statement - that is, since map[startY][startX] is already 3 - the last statement is just skipped.

To be honest I think the real problem here is your use of the for statement. Even in the parts where it works correctly you're using it in a very unnatural and unidiomatic way. Much better would be (for instance):

while (map[y][x - 1] == 3) --x;

In the "restart" case that isn't working, the natural thing to do would be to skip out the for statement entirely:

else if(key[KEY_R] && map[startY][startX] == 3)
{
  y = startY;
  x = startX;
}