C-持续崩溃的ADT

Question

I'm trying to create an ADT , first of all, here is the basic information about it:

typedef struct orange_t* Orange;

typedef enum {
JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC,
} Month;

struct orange_t {

short size;
Month expirationMonth;
char** foodCompanies;
int maxNumberOfFoodCompanies;
int sellingPrice;
};

now im trying to create a function that will "create" new orange like that:

Orange orangeCreate(short size,Month expirationMonth
    ,int maxNumberOfFoodCompanies,int sellingPrice)
 {
   Orange new_orange=(Orange)malloc(sizeof(struct orange_t));
   if(new_orange==NULL)
   {
        return NULL;
    }
   if((sellingPrice<0)||(size>256||size<1)||(maxNumberOfFoodCompanies<0)||(expirationMonth>12)
        ||(expirationMonth<1))
        {
        return NULL;
        }
new_orange->sellingPrice=sellingPrice;
new_orange->maxNumberOfFoodCompanies=maxNumberOfFoodCompanies;
new_orange->expirationMonth=expirationMonth;
new_orange->size=size;
for(int i=0;i<new_orange->maxNumberOfFoodCompanies;i++)
{
    new_orange->foodCompanies[i]=NULL;
}
return new_orange;
}

when I tried to check the function with the simple main() :

int main()
{
Orange orange=orangeCreate(3,JAN,10,4);
printf("the size is %d\n",orange->size);
orangeDestroy(orange);
return 0;
}

the program keeps crashing, I guess I didn't change the values in orange as I should, and they might still be NULL . where did I go wrong here?

Answer 1

JAN is 0. if expirationMonth<1 you are returning NULL from orangeCreate .

Also: you are not checking the return value of orangeCreate . And you are leaking memory in orangeCreate when you are just returning NULL without free ing the allocated new_orange .

Answer 2

The problem is that you are not allocating memory for char** foodCompanies;

---

While allocating memory here

Orange new_orange=malloc(sizeof(struct orange_t));

You have allocated space for the pointer variable char** foodCompanies; , but have not allocated space where it would point to.

Answer 3

You have to allocate some memory and store the address of it to new_orange->foodCompanies before accessing it.

Possible fix:

Orange orangeCreate(short size,Month expirationMonth
    ,int maxNumberOfFoodCompanies,int sellingPrice)
 {
   Orange new_orange=malloc(sizeof(struct orange_t));
   if(new_orange==NULL)
   {
        return NULL;
    }
   if((sellingPrice<0)||(size>256||size<1)||(maxNumberOfFoodCompanies<0)||(expirationMonth>12)
        ||(expirationMonth<1))
        {
        return NULL;
        }
new_orange->sellingPrice=sellingPrice;
new_orange->maxNumberOfFoodCompanies=maxNumberOfFoodCompanies;
new_orange->expirationMonth=expirationMonth;
new_orange->size=size;
new_orange->foodCompanies=malloc(sizeof(char*)*new_orange->maxNumberOfFoodCompanies); /* add this line */
for(int i=0;i<new_orange->maxNumberOfFoodCompanies;i++)
{
    new_orange->foodCompanies[i]=NULL;
}
return new_orange;
}

Note: it is discouraged to cast the result of malloc() in C.
c - Do I cast the result of malloc? - Stack Overflow