Thread: passing/pointing to a 2d array

I have a 2d array as so:

PHP Code:

char array[num_of_files][100]; 


and a pointer

PHP Code:

char* p; 


which points to the array as so

PHP Code:

p = array; 


I want to pass this pointer to another function, and access the array from that function.

PHP Code:

new_func(p); 


New function is declared like so

PHP Code:

int new_func(char* p); 


In the new function, i cant cant seem to move along the 2d array.

What am i doing wrong??

Thanks

New function is not declared correctly. Declare like so:

Code:

int new_func(char p[][100])

Otherwise the new_func code doesn't know how to calculate the offsets when you do p[1][5] (how does it know how to get to the next row without knowing the row size?)

Have a good read of this FAQ:

http://www.eskimo.com/~scs/C-faq/s6.html

Pay particular attention to 6.18.

Code:

char array[num_of_files][100]; 
char **p = array; 

int new_func(char **p)
{
}

new_func(p);

Originally Posted by rockytriton

Code:

char array[num_of_files][100]; 
char **p = array; 

int new_func(char **p)
{
}

new_func(p);

You too should read the exact same FAQ I mentioned above. A pointer to a pointer is not the same as a two dimensional array.

Originally Posted by cwr

New function is not declared correctly. Declare like so:

Code:

int new_func(char p[][100])

Otherwise the new_func code doesn't know how to calculate the offsets when you do p[1][5] (how does it know how to get to the next row without knowing the row size?)

Have a good read of this FAQ:

http://www.eskimo.com/~scs/C-faq/s6.html

Pay particular attention to 6.18.

Thankyou thankyou. Works a like a dream now. Good FAQ also.

Cheers.

Originally Posted by cwr

You too should read the exact same FAQ I mentioned above. A pointer to a pointer is not the same as a two dimensional array.

That's for clearing that up for me, I always thought it was the same, I've used it like that in the past a lot.

Originally Posted by rockytriton

That's for clearing that up for me

You're welcome.

I always thought it was the same, I've used it like that in the past a lot.

No you haven't, or you'd get instant garbage or a memory access error when you tried to access the elements in the function.