Thread: structs

hey guys just wondering how i could access a member from the structure definitions below but access it from a function called systemInit like the one below.

iv tried going menu->PriceType->dollars; but that wont work it says there is no member.

And 1 other question if i needed to intialize the struct members which ones would i need to initialize this eventually is also going to be used for linked lists?

Code:

typedef struct category* CategoryTypePtr;
typedef struct item* ItemTypePtr;

/* Structure definitions. */
typedef struct price
{
   unsigned dollars;
   unsigned cents;
} PriceType;

typedef struct item
{
   char itemID[ID_LEN + 1];
   char itemName[MAX_NAME_LEN + 1];
   PriceType prices[NUM_PRICES];
   char itemDescription[MAX_DESC_LEN];
   ItemTypePtr nextItem;
} ItemType;

typedef struct category
{
   char categoryID[ID_LEN + 1];
   char categoryName[MAX_NAME_LEN + 1];
   char drinkType;      /* (H)ot or (C)old. */
   char categoryDescription[MAX_DESC_LEN];
   CategoryTypePtr nextCategory;
   ItemTypePtr headItem;
   unsigned numItems;
} CategoryType;

typedef struct gjc
{
   CategoryTypePtr headCategory;
   unsigned numCategories;
} GJCType;

Code:

void systemInit(GJCType* menu)
{
}

try this menu->headCategory->headitem->prices[index].dollars

i get headitem that there is no member

it works but how come when i go ->dollars it dosnt like the -> instead i have to put the

full stop .dollars im using ansi c on unix

remember the use 0f -> is when u access the structure members using a pointer of type that structure

and . is used when access the structure members using a normal variable of type that structure

for example

Code:

struct somename
{
     int somedata1;
     int somedara2;
};

//using normal varibale
struct somename name;

//uisng structure pointer
struct somename *nameptr;

//access that data
name.somedata1;
name.somedata2;

nameptr->somedata1;
nameptr->somedata2;

ssharish2005

also mate if i declare the member like this
menu->headCategory->headItem->prices[somenumberhere]->dollars = 0

how come i get a segmentation error?

what is your array size

Code:

PriceType prices[NUM_PRICES];

i mean NUM_PRICES value ->????

it seems that u crossing the array boundary

ssharish2005

the array size of NUM_PRICES is 3

so what is the value of somenumberhere -> ???

if this is more than 3 u might well get some error like SEG FAULT

ssharish2005

menu->headCategory->headItem->prices[3]->dollars = 0

thats how it is but i get a seg fault

given the declarations from the first post

Code:

menu->headCategory->headItem->prices[somenumberhere]->dollars = 0

shouldn't compile
Kurt

menu->headCategory->headItem->prices[somenumberhere].dollars = 0

i changed it to this and now it does compile

I know.

but why when i runnit do i get a seg fault