c - What's wrong with my print_random_sprites function? -

i'm writing code in c randomly displays sprites on lcd screen on microprocessor. when run code produces 8 lines running top bottom. it's printing in random order not sprite. why this? me? (note: rand seeded in separate function works fine, problem within code.)

void zombies() {      sprite zombie_sprite;     sprite * zombie_sprite_pointer = &zombie_sprite;     byte zombie_bitmap [] = {     byte( 11100000 ),     byte( 01000000 ),     byte( 11100000 ) };      (int = 0; < 8; i++) {         sprite * zombie_sprites = &zombie_sprites[i];         init_sprite(zombie_sprites, rand()%76, rand()%42, 3, 3, zombie_bitmap);         }     create_zombies();        }  void create_zombies(sprite * zombie_sprites) {     while(1) {     clear();     draw_sprite( &zombie_sprites );     refresh();     }     return 0; } 

the main problem sprite zombie_sprite 1 object. make array of objects , can start looking @ other problems. next there fair bit of confusion on pointers sprite objects. simplify things bit can tweak variables in zombies function, along 'tidying up' best practices.

// start using compile-time constant define number of zombies. // changed vriable in the, once simple case working. #define number_of_zombies 8  void zombies() {     // 8 zombies required, define array of 8 sprites.     sprite zombie_sprites[number_of_zombies];     byte zombie_bitmap [] =      {         byte( 11100000 ),         byte( 01000000 ),         byte( 11100000 )     };  // continued below... 

this makes rest of function initialise sprites easier. time, possible pointer ith element in array. also, see create_zombies function requires argument: address of sprite object, pass address of first sprite in same array has been initialised.

again, bit of housekeeping, rest of function this:

    // ...continued above      (int = 0; < number_of_zombies; i++)     {         // initialise ith sprite using address of element         // in zombie_sprites array.         init_sprite(&zombie_sprites[i], rand()%76, rand()%42,                     3, 3, zombie_bitmap);     }      // animate zombies in array.     create_zombies(&zombie_sprites[0]);        } 

finally, create_zombies function needs minor change loop through of sprites in array passed parameter. also, being of type void not have return statement.

void create_zombies(sprite * zombie_sprites) {     while(1)     {         clear();          // loop round drawing of sprites.         for(int zombie_index = 0; zombie_index < number_of_zombies; zombie_index++)         {             draw_sprite( &zombie_sprites[zombie_index] );         }          refresh();     } } 

future enhancements might include:

• changing number_of_zombies variable.
• replacing static array dynamically allocated array using malloc , free.
• replacing array more complex abstract data type such list or doubly linked list, zombies can added or removed @ run-time.
• renaming functions , restructuring each gets called.