来自数组指针的正确语法访问值？

Question

(I realize there aa zillion questions and answers on SO pertaining arrays and pointers but after wading through many of them, I'm still not getting it.)

Question: What is the proper syntax access values from an array pointer?

Background: What I am doing is very simple: I'm defining some arrays and then defining an array which points to those arrays (code below). I am doing this so that I can reference my 'circle' arrays in a for..loop. (I realize I can skip pointers altogether by just defining a multidimensional array but for ease of coding and fast changes at this stage, it would be helpful to define the 'circle' arrays just once).

I am running into problems when I try to access the array data. This complies but the data is garbage:

for (int i = 0; i < circleArrayLength; i++) {

   for (int c = 0; c < 6; c++) {
    byte *index = circleArray[i][c]; // WRONG

    writeBufferSingle(basePattern[*index][0], basePattern[*index][1], 1);
   }
   writeScreen();
   delay(50);
}

So then, what is the proper syntax access values from an array pointer?

---

byte circle0[7] = { 0, 1, 40, 44, 43, 42, 41 };
byte circle1[7] = { 1, 2, 39, 45, 44, 41, 40 };
byte circle2[7] = { 2, 3, 38, 46, 45, 40, 39 };
byte circle3[7] = { 3, 4, 37, 47, 46, 39, 38 };
byte circle4[7] = { 4, 5, 36, 48, 47, 38, 37 };


byte* circleArray[][7] = { circle0, circle1, circle2, circle3, circle4}

Answer 1

 byte* circleArray[][7] = { circle0, circle1, circle2, circle3, circle4} 

This is almost certainly wrong. circleArray should not be an array of arrays of byte* .

byte circleArray[][7] = { circle0, circle1, circle2, circle3, circle4};

...

byte index = circleArray[i][c];

writeBufferSingle(basePattern[index][0], basePattern[index][1], 1);

Also, consider storing circle<n> and circleArray in flash instead.

Answer 2

There are two method to do that.

Method one:

#include <stdio.h>

typedef char byte;

int main(void)
{
    byte circle0[7] = { 0, 1, 40, 44, 43, 42, 41 };
    byte circle1[7] = { 1, 2, 39, 45, 44, 41, 40 };
    byte circle2[7] = { 2, 3, 38, 46, 45, 40, 39 };
    byte circle3[7] = { 3, 4, 37, 47, 46, 39, 38 };
    byte circle4[7] = { 4, 5, 36, 48, 47, 38, 37 };

    byte *circleArray[] = { circle0, circle1, circle2, circle3, circle4};

    size_t circleArrayLength = sizeof(circleArray)/sizeof(circleArray[0]);

    for (size_t i = 0; i < circleArrayLength; i++) {
        for (size_t c = 0; c < 7; c++) {
            printf("circleArray[%zu][%zu] = %d\n", i, c, circleArray[i][c]);
        }
    }
}

Method Two:

#include <stdio.h>

typedef char byte;

int main(void)
{
    byte circle0[7] = { 0, 1, 40, 44, 43, 42, 41 };
    byte circle1[7] = { 1, 2, 39, 45, 44, 41, 40 };
    byte circle2[7] = { 2, 3, 38, 46, 45, 40, 39 };
    byte circle3[7] = { 3, 4, 37, 47, 46, 39, 38 };
    byte circle4[7] = { 4, 5, 36, 48, 47, 38, 37 };

    byte (*circleArray[])[7] = { &circle0, &circle1, &circle2, &circle3, &circle4};

    size_t circleArrayLength = sizeof(circleArray)/sizeof(circleArray[0]);

    for (size_t i = 0; i < circleArrayLength; i++) {
        for (size_t c = 0; c < 7; c++) {
            printf("circleArray[%zu][%zu] = %d\n", i, c, (*circleArray[i])[c]);
        }
    }
}