I made a data type:

typedef struct Sale_t *Sale;
struct Sale_t
{
    int license;
    int km_min;
    int km_max;
    int price;
};

I am creating it with this function:

Sale saleCreate(int license, int km_min, int km_max, int price,List sales)
{
    if(saleFind(sales,license)==RENTAL_CAR_ALREADY_ON_SALE)
    {
        return NULL;
    }
    if(km_min<0||km_max<=km_min||price<=0)
    {
        return NULL;
    }
    Sale salePtr = malloc(sizeof(*salePtr));
    if(!salePtr)
    {
        return NULL;
    }
    salePtr->license=license;
    salePtr->km_min=km_min;  //here it crashes
    salePtr->km_max=km_max;
    salePtr->price=price;
    return salePtr;
}

(Don't mind about Sale and Sale_t; I'm using a typedef in a header file so it's not a problem at all.)

After some testing, I have found out that if salePtr->km_min gets any integer other than 0, the program cras开发者_高级运维hes.

What causes this? I'm sure it's something to do with malloc()...

EDIT

i made a similar data type which works PERFECTLY:

typedef struct Car_t *Car;
struct Car_t
{
    int license;
    char* name;
    int price;
    int km;
    int renterId;
};
Car carCreate(int license, char* name, int price, int km, List cars)
{
    if(carFind(cars,license)==RENTAL_CAR_ALREADY_EXISTS)
    {
        return NULL;
    }
    if(km<0||price<=0)
    {
        return NULL;
    }
    Car carPtr = malloc(sizeof(*carPtr));
    if(!carPtr)
    {
        return NULL;
    }
    carPtr->km=km;
    carPtr->license=license;
    carPtr->name=name;
    carPtr->price=price;
    carPtr->renterId=0;
    return carPtr;
}

This is wrong:

Sale salePtr = malloc(sizeof(*salePtr));

Should (probably) be:

Sale *salePtr = malloc(sizeof(Sale));

I say probably because you're using Sale which you don't define in the code you've pasted, so it may be typedef'd to a pointer type already.

EDIT

Since the OP has typedef'd Sale to Sale_t*, it should look like this:

Sale salePtr = malloc(sizeof(Sale_t));

This line is wrong:

Sale salePtr = malloc(sizeof(*salePtr));

You used an identifier salePtr, before it was defined (or well, in the definition itself). This should work:

Sale salePtr = malloc(sizeof(*Sale));

However, since we are actually allocating memory for a Sale_t this seems more logical to me:

Sale salePtr = malloc(sizeof(Sale_t));

Since the OP mentions that

typedef Sale_t* Sale

was used, here is what needs to be done

Use this for alloc

Sale salePtr = (Sale)malloc(sizeof(Sale));

Use this for return

return salePtr;