C - Honestly at a loss for this odd behaviour -

so... have little piece of code have been working on of morning. it's little project me remember syntax , on. have missed kind of massive error code returns segmentation fault reasons don't understand.

#include <stdio.h> #include <stdio.h> #include <unistd.h> #include <time.h> #include <getopt.h>  struct cards  { int card_value[99]; char card_name[99]; char card_suit[99]; int card_tally; };  struct cards hand[2];  void tally (int a) { int k, j; (k=0; k<5; k++)  {   j = j + hand[a].card_value[k];  } hand[a].card_tally = j;  }   void check_for_ace (int a)  { int d; (d=0; d>5; d++)   {      if (hand[a].card_name[d] =='a')       {           int y;           int z = 10;           (y=0; y<5; y++)             z = z + hand[a].card_value[y];           if (z < 22)             hand[a].card_value[d]=10;           else             hand[a].card_value[d]=1;       }     } }  void draw_card (int a) { int z = 1 + rand () % 13; int x=0;  while (hand[a].card_value[x] !=  0)     { x++; }  if ((z > 1) && (z < 10))   {       hand[a].card_value[x]=z;       hand[a].card_name[x]=((char) '0' + z);   } else if (z == 10)   {       hand[a].card_value[x]=z;       hand[a].card_name[x]='t';   } else if (z == 11)   {       hand[a].card_value[x]=10;       hand[a].card_name[x]='j';   }    else if (z == 12)   {       hand[a].card_value[x]=10;       hand[a].card_name[x]='q';   } else if (z == 13)   {       hand[a].card_value[x]=10;       hand[a].card_name[x]='k';   } else if (z == 1)   {       /*function 'check_for_ace' deals more properly*/       hand[a].card_value[x]=1;       hand[a].card_name[x]='a';   }  check_for_ace(a);  tally(a); }    void display_hands () { int x; printf("\ndealer's hand shows: "); (x=0; hand[0].card_name[x]!=0; x++)   {       printf("%c ", hand[0].card_name[x]);   }  printf("\nplayer's hand shows: "); (x=0; hand[1].card_name[x]!=0; x++)   {       printf("%c ", hand[1].card_name[x]);   } }  void dealer_turn() {   while (hand[0].card_tally < 17)   draw_card(0); }  void player_turn() { int op=0; while (op != 2)   {     printf("what do?\n");     printf("(1)it or (2)tand\n");     scanf("%d", &op);      if (op == 1)      draw_card(1);    } }     int main(int argc, char **argv) { srand(time(null));       draw_card(0);     draw_card(1);     draw_card(1);     display_hands();     player_turn();      dealer_turn();     display_hands();  return 0; } 

now, odd thing is, see empty line between player_turn , dealer_turn? if put display_hands in there code executes without error.

any ideas?

also, realize did use headers don't require. plan use them later , left them in post have left error.

you aren't initializing j before execute line.

  j = j + hand[a].card_value[k]; 

when added j=0 initialization code, no longer crashes.

e.g.

void tally (int a) { int k, j; j=0;  /* <----- added line */ (k=0; k<5; k++)  {   j = j + hand[a].card_value[k];  } hand[a].card_tally = j;  }