Thread: New at Array and Pointers , Quick Question

Okay i was reading up on array and pointers, i have a function which requires the following input below and i want to know if im correctly placing the syntax for it :

Code:

#include <cextdecs(PROCESS_GETINFOLIST_)>
short PROCESS_GETINFOLIST_ (short *ret-attr-list ,short ret-attr-count ,short *ret-values-list ,short ret-values-maxlen ,short *ret-values-len )

Code:

short *ret_val_length;
short attr_list[3] ={2,4,22};
short vals_list[20];
short *ret_attr_list = attr_list ;
short *ret_vals_list= vals_list;
short ret_attr_count = 3;
short ret_values_maxlen = 8192;

main()
{
  result = PROCESS_GETINFOLIST_ (&ret_attr_list, ret_attr_count, &ret_vals_list, ret_values_maxlen, &ret_val_length);

Also my question is the unary & operator required for &ret_attr_list? if im referencing the entire array?!
Thank you for the help.

You need to pass a short*. If your variable is a short* already, then taking & will make it Something Else.

So the & is not required, in the book it says the & is used to retrieve the address and copy it to the content of the pointer.

Yes. &ret_attr_list is the address of ret_attr_list. That's not what you want, though; you want the address of the data (the bunch of shorts) itself. The value of ret_attr_list is the address of the data itself.

The definition of ret_val_length is wrong. You declared it as a pointer, then pass it in by address (which is a short **, not a short *). Also, it doesn't actually point to a valid memory location that contains a short, it points into some random place that will likely cause your program to crash. You want to declare it as a plain old short, and pass in the address, like so:

Code:

short ret_val_length;
...
result = PROCESS_GETINFOLIST_ (ret_attr_list, ret_attr_count, ret_vals_list, ret_values_maxlen, &ret_val_length);

Also, you can't use a hyphen in an identifier name, so in your prototype, ret-attr-list et al, should be changed to something like ret_attr_list. Identifiers should start with a letter, and contain only letters, numbers and underscore.