Re: Need Orca/C help...

[tsang@cs.washington.edu (Donald Tsang)]

In article <> jlee@Bonnie.ICS.UCI.EDU ("Joseph T. Lee") writes:
>The difference comes from what kind
>of code you write to access them.  Well using calloc it would be:
>
>int *array;
>array = (int *) calloc(100 * 100, sizeof(int));
>
>then you access it like any other array:
>
>array[5][10] = 1
>getvalue = array[5][10]


No no no... because it was allocated as a single piece of memory, it
has no idea whatsoever how big the "rows" are.

You may be able to declare a pointer-to-small-array, like
int (*array)[10];

but I can never get those right...


>BTW, you can do this with any pointer, it's just not efficient. That's where
>pointer math comes in, but (hint, hint :) it's something you should look at.

No, the compiler usually converts freely between p[i] and *(p+i)...
shouldn't make a difference.


>I don't suggest using calloc nor malloc calls unless you know what you're
>doing and you're writing really weird code. The simple initialization during
>the declaration of the array should be just fine.

Only if it's supported, and only the first time.  If you have to
reinitialize, you're screwed.


-- 
Donald Tsang         tsang@cs.washington.edu       ...!uw-beaver!june!tsang

       A radioactive cat has 18 half-lives   -- [/usr/games/fortune]