Copy a string on a structure element in C - c

Question

I don't understand why my string is not copied.
The strings structures are similar to this one "KS 2H 5C JD TD"
Here is my code (the comments are all that I tried (memcpy and strcpy)):
typedef struct Hand Hand;
struct Hand {
char *cards;
double power;
};
Hand* initHand(char *set){
Hand *hand = malloc(sizeof(*hand));
if(hand == NULL)
exit(EXIT_FAILURE);
char card[5][3];
//strcpy(hand->cards,*cards);
int i=0;
char *p = strtok (set, " ");
while (p != NULL)
{
card[i] = p;
printf("%s\n",p);
p = strtok (NULL, " ");
i++;
}
hand->power=0;
}
I was willing to copy every 2 letters in an array with strtok (this is what I wanna do); then I tried to copy the whole string.

Answer 1

Thanks a lot. I understood my mistakes:
Mistakes:
I didn't know that strtok is a destructive function (I was trying to edit a readonly data since I was using a constant).
I didn't allocate memory for char *cards
Solution:
make a copy of the set.
allocate memory.
Here's the code that worked for me:
struct Hand {
char cards[5][3];
double power;
};
Hand* initHand(char *set){
Hand *hand = malloc(sizeof(*hand));
if(hand == NULL)
exit(EXIT_FAILURE);
char copy_set[15]="";
strcpy(copy_set,set);
char **str = (char**) malloc(5*sizeof(char*));
for(int i=0; i<3; i++){
str[i]= (char) malloc(3*sizeof(char));
}
strcpy(hand->cards,str);
int i=0;
char *p = strtok (copy_set, " ");
while (p != NULL)
{
strcpy(hand->cards[i], p);
p = strtok (NULL, " ");
i++;
}
hand->power=0;
return hand;
}

Answer 2

I think that this is reasonably correct code — a relatively simple modification of the code shown in revision 2 of the answer by the OP. There's always room for improvement, of course.
#include <stdlib.h>
#include <string.h>
struct Hand
{
char cards[5][3];
double power;
};
typedef struct Hand Hand;
extern Hand *initHand(const char *set);
Hand *initHand(const char *set)
{
Hand *hand = malloc(sizeof(*hand));
if (hand == NULL)
exit(EXIT_FAILURE);
char copy_set[15] = "";
strcpy(copy_set, set);
int i = 0;
char *p = strtok(copy_set, " ");
while (p != NULL)
{
strcpy(hand->cards[i++], p);
p = strtok(NULL, " ");
}
hand->power = 0;
return hand;
}
#include <stdio.h>
int main(void)
{
Hand *hand = initHand("KS 2H 5C JD TD");
for (int i = 0; i < 5; i++)
printf("Card %d: [%s]\n", i, hand->cards[i]);
printf("Power: %.2f\n", hand->power);
free(hand);
}
As I noted in a comment, the variable str isn't needed. With the revised structure, there is no need to allocate extra cards. I've marked the string input as const. Arguably, it would be better to do a dynamic memory allocation for copy_set (remembering to release the copy too), or at least check that the given data will fit in the allocated space. It would probably be better to print an error message before unilaterally exiting on a memory allocation failure. It is good to check for the failure. It is not good to exit with saying why. It would probably be better to return NULL on failure, and then let the calling code detect and handle the problem.
There's a simple test program attached to the code too.
Be cautious about using strtok(); it is dangerous to use it in library functions. You should generally use strtok_r() (POSIX) or strtok_s() (Microsoft) for preference.