[ale] Any C Gurus Out There

[Terry Lee Tucker]

Hello,

I have a C question. I am experiementing with pointers. I want to be able to 
dynamically allocate a three dimensional array (a table of strings) and I 
want to be able to be able to allocate all the parts of the array using 
pointers. Yes, I know I can use subscripts and yes, I know that would be 
easier to read; but, I just want to be "able" to do it. Here's what I've 
discovvered so far:
char ***threeD;
threeD = (char ***) calloc (2, sizeof (char **));

This line works, and allocates space for two rows. I know tthat it works 
because I have used subscripts to allocate, populate and print the contents 
of the array.

I have a pointer row3d defined as:
char ***row3d;
row3d = threeD;
*row3d++ = (char **) calloc (5, sizeof (char *));
*row3d = (char **) calloc (5, sizeof (char *));

This allocates memory for the two rows and apparently is equivalent to:
threeD[0] = (char **) calloc (5, sizeof (char *));
threeD[1] = (char **) calloc (5, sizeof (char *));

This is where the problem starts. I have a pointer defined as:
char ***row0col;
row0col = threeD;

I want to use row0col to allocate memory for each column in row 0 and copy a 
string to that address. I thought this would work:
**row0col = (char *) calloc (20, sizeof (char));
strcpy (**row0col, "row:0;col:0");
*(*row0col)++;

But, it doesn't. The first element, column 0, gets copied correctly but I am 
unable to get the pointer to increment correctly so I can allocate a new 
block of memory for the next string in column 1; I have tried many different 
pointer incrementation schemes other that the above. Most don't increment it 
at all. The ones that do, apparently by viewing through gdb, either increment 
the address to the next character in row 0 column 0 or increment the entire 
row.

I can do all of this with subscripts and it works fine. I just can't figure 
out the pointer equivalent to threeD[y][x] and how to increment that with 
pointer arithmetic. If anyone has a clue on this, I would appreciate your 
insight. I'm sure others would as well.

Thanks..

PS: The source file is attached.
-- 
Quote: 59
"The concessions of the weak are the concessions of fear."

 --Mark Twain

 Work: 1-336-372-6812
 Cell: 1-336-363-4719
email: terry at esc1.com
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