pointer, array arithmetic

[yaya]

question about pointer and array.
can we add a 2-D array (**A) with a 1-D array (*B)? both of the array is define as a pointer in the program.
where array A is A[i][j] and B is B[i]

how to get call back a value of a pointer? for example A[i][1] and is it possible to redefine it as a 1-D array?

i find that the pointer is the most confusing thing in C language....need help...

[Banfa]

An array is just a section of memory large enough to contain a number of values be it 1, 2 or more dimensions. However memory is physical and (generally) is only 1 dimensional.

If your arrays are defined as so

#define DIMENSION_1 10
#define DIMENSION_2 20

typedef <TypeInQuestion> TYPE;

TYPE A[DIMENSION_2][DIMENSION_1];

TYPE B[DIMENSION_1];

then A[n] has the same type as B and could be copied to B (or vis versa).

Arrays are not a thing and can be "added" and I am not quite sure what you mean by this.

However defining C like this

TYPE **C;

and the array A defined above are not the same thing at all. The array A has set dimensions and has memory allocated to hold all values you can access any element by A[i][j].

C is just a pointer, it is not an array at all but a pointer to a pointer to TYPE. C[i][j] does not do what you thing it does, and certainly not the same as A[i][j].

C is pointer to pointer to type, so C is a pointer if you use it as an array, C[i], you will reference an array that has type pointer to TYPE (TYPE *) not an array of type TYPE [DIMENSION_1] as A[i] would be.

since sizeof(TYPE *) is unlikely to be equal to sizeof(TYPE [DIMENSION_1])

A[i] and C[i] are not equivilent.

If you want to use a pointer as a 2 dimensional array then you do it like this

TYPE D[DIMENSION_2][DIMENSION_1];
TYPE *E = &D[0][0];

then

D[i][j]

and

E[i*DIMENSION_1+j]

will access the same element of D.