Passing arrays into a function,

[countdrak]

int main()
{
   int my_arr[3] = {1, 2, 3};
   ....
   my_fun(my_arr);
}

void my_fun(int array[])
{
  /*need to determine the number of elements in array*/
  x = num_of_items_in_array;
  /*perform computation*/
}

It so happens that there is no clear way to determine the num of items in a passed array, since integer arrays are not null terminated.

Can anyone help me here? Or would I have to explicitly tell the function how many items are there int he given array?

 

[sedj]

I believe you will need to tell the function the number of elements :

int main()
{
   int my_arr[3] = {1, 2, 3};
   ....
   my_fun(&my_arr[0], 3);
}

void my_fun(int* piArray, int iArrayLen)
{
  /*need to determine the number of elements in array*/
  x = num_of_items_in_array;
  /*perform computation*/
}

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[marsd]

int main(void) {
int arrayname[5] = {1,2,3,4,5};
int wrongnum[20] = {1,2,3,4,5,6,7,8,9,0};
                   printf("arrayname = %d elements\nwrongnum = %d elements\n",asz(arrayname),asz(wrongnum));
		   return 0;
}

Of course if you want an accounting of the actual number
of valid entries in the array according to whatever criteria you will have to devise that yourself.

HTH

 

[marsd]

Oops..the asz macro...

#define asz(a) ((sizeof(a) / sizeof(a[0])))

 

[ArkM]

Be careful: don't use asz macros in function body!

void my_fun(int array[],...)
/* sizeof(array) treated as a pointer size! */

So read sedj's adivice again. You can't obtain array argument size via its parameter only (in C and C++).