Thread: pointer intializing to

Originally Posted by ronenk

run this code OK. How do I modify it so I don't have to use the t veriable.

Code:

int mat[N][N]={{2,4,6,8},{24,8,3,10},{22,1,8,12},20,18,16,14}};
	int t, *d;
	t=mat[0][1]-mat[0][0];
	d=&t;

You want the address of a variable, but you don't want this variable? Impossible. Be more specific.

You can't. t is an integer, which is storing the result of two integers being subtracted. Thus, it give you an integer. If you want a pointer to an integer, you have to have at least one integer to point to. What your code does, in effect is this:

Code:

int t, *d;
t = 4 - 2; /* make t store something, doesn't matter what */
d = &t; /* make d point to t */

You have to have an integer for your pointer to point at. In short, all pointers must have something to point at.

[edit]Curses, foiled again.[/edit]

Quzah.

mabey

Code:

int *d;
d = malloc(sizeof(int));
*d  = 4 - 2; /* :) */

>>mat[0][1]-mat[0][0];
That evaluates to an r-value, or basically _a number_, meaning it isn't stored at any particular memory location that you can point at with a pointer. It's like saying:

int* d = &2;

The only solution I can see is something along the lines of what chrismiceli posted, although that is messier and harder to use than the method involving the 'int t;'. In fact, it does pretty much the same thing, except that the variable is allocated on the heap instead of the stack, and d points to the heap-variable which you then have to free() after you're done with it.

It seems to be down That happens once in a while (very annoying), but it usually goes back up in a day or two. Sorry!