Thread: Condition of the for loop with defined arraylength(*array)

Hi!

EDIT: this was an irrelevant post - the array size is specified in the program I am referring to, so no magic. I can't delete the post, so I am sorry if you have lost your time reading it.

Please, help me to understand how the size of the array is used in the following part of the program, which I have found on this forum.
We define the size of the array as

Code:

#define ARRAYLENGTH(x) (sizeof(x)/sizeof(*(x)))

Then in the program we get information from the file and put that into the array using the for loop. My question about the condition of the loop

Code:

j < ARRAYSIZE(*array)

: when the loop starts, the array is not yet populated, so the size is equal to sizeof(the whole array which is null at the first iteration of the loop)/sizeof(first member of the array)). Please, help me to understand how this condition works, and how to interpret it.

Code:

      for ( i = 0; fgets(buffer, sizeof buffer, file); ++i )
      {
         for ( j = 0, ptr = buffer; j < ARRAYLENGTH(*array); ++j, ++ptr )
         {
            array[i][j] = (int)strtol(ptr, &ptr, 10);
         }
      }

Thanks a lot!