How to print a 2D-array in C, without using the operator []?

问题

I am trying to print a 2D matrix with using [], instead I want to use * like a pointer.
So with a 1 D array I'd do: *(arr+i) for example. What's the syntax used to replace in matrix[][] ?

Here's the code:

for (i = 0; i < size; i++)
{
    for (j = 0; j < (size * 2); j++)
    {
        printf(" %5d", matrix[i][j]);
    }
    printf("\n");
}

P.S, I did try several things like:

*(matrix+i+j);
*(matrix+i)+*(matrix+j);

Of course none of that worked.

Thank you for your help and time!

回答1:

This may depend on how matrix was allocated or passed to a function.

int A[10][15];

This uses a contiguous block of memory. To address the elements without using array notation use:

        A +(i*15)+j    // user694733 showed this is wrong
((int *)A)+(i*15)+j    // this is horribly ugly but is correct

Note the 15, as each row consists of 15 elements. Better solutions are presented in other answers here.

In the following:

int *A[10];

A is an array of 10 pointers to ints. Assuming each array element has been allocated using malloc, you address the elements without using array notation as:

*(A+i) + j;

that is, you take A, then take the ith element, dereference that and add j as the second index.

--EDIT--

And to be complete:

int foo(int *p)

here a function just receives a pointer to zero or more ints. The pointer points to a contiguous, linear block of memory into which you can place an n-dimensional array. How many dimensions there are and the upper bound of each dimension the function can only know through parameters or global variables.

To address the cells of the n-dimensional array, the programmer must calculate the addresses him/herself, using the above notation.

int foo3(int *m, int dim2, int dim3, int i,  int j, int k)
{
    int *cell = m + i*dim3*dim2 + j*dim2 + k;
    return *cell;
}

回答2:

Use the * two times. Each of * will basically replace one []:

*(*(matrix+i)+j)

回答3:

You can try this-

*(*(matrix+i)+j)  //reduce level of indirection by using *

来源：https://stackoverflow.com/questions/35312840/how-to-print-a-2d-array-in-c-without-using-the-operator

标签

arrays

pointers

syntax-error