Question

I need to check if an array is empty using macros. If the size of array is constant say 2, then I will be able to write a macro like

#define IS_EMPTY(arr)  \
  ((arr[0] | arr[1]) == 0) 

But if arr is defined like this

#define ARRAY_SIZE 100
int arr[ARRAY_SIZE];

Is there any way, a macro can determine that the array is empty? Or is inline functions the only option.

Answer 1

Your most viable options would be a loop:

int IsEmpty(char * array, size) {
 int i;
 for (i=0; i<size; i++)
   if (array[i] != 0)
      return 0;
 return 1;
}

or memcmp:

int IsEmpty(char * array, size) {
 char * emptyArray = malloc(size);
 memset(emptyArray, 0, size);
 int res = memcmp(array, emptyArray, size);
 free(emptyArray);
return res==0;
}