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up vote 0 down vote favorite

How would i go about creating an array of variables such as.....

int incColor, c0, c1, c2, c3, c4, c5 = 0;
int circleArray[11][9] = { {c5, c5, c5, c5, c5, c5, c5, c5, c5}, 
                             {c4, c4, c4, c4, c4, c4, c4, c4, c4}, 
                             {c4, c3, c3, c3, c3, c3, c3, c3, c4}, 
                             {c4, c3, c2, c2, c2, c2, c2, c3, c4}, 
                             {c4, c3, c2, c1, c1, c1, c2, c3, c4}, 
                             {c4, c3, c2, c1, c0, c1, c2, c3, c4}, 
                             {c4, c3, c2, c1, c1, c1, c2, c3, c4}, 
                             {c4, c3, c2, c2, c2, c2, c2, c3, c4}, 
                             {c4, c3, c3, c3, c3, c3, c3, c3, c4}, 
                             {c4, c4, c4, c4, c4, c4, c4, c4, c4}, 
                             {c5, c5, c5, c5, c5, c5, c5, c5, c5} };

So that later on in the code i will be able to address them like this...

void circle(uint16_t mode) 
{
  switch (mode)
  {
     case 0:
     c0 = random(255);
     break; 
     case 1:
     c0 = incColor;
     incColor++;
     break;
  }
  for (int x = 0; x < 11; x++)
  {
     for (int y = 0; y < 9; y++)
    {
       strip.setPixelColor(x, y, Wheel(circleArray[x][y]));
    } 
  }
  c5 = c4;
  c4 = c3;
  c3 = c2;
  c2 = c1;
  c1 = c0;

}

The code above doesnt work, i tested both c5 and circleArray[0][0]

c5 = 34
circleArray[0][0] = 0

circleArray[0][0] should be the same as c5 is what i thought but for some reason the value is not getting set...

Does anybody know what im doing wrong here?

~~~~~~~~~~~~~~EDIT~~~~~~~~~~~~~~~~~

Fixed!! thanks to @sj0h for helping me see a much easier solution so now i can turn this...

int c[6] = {0, 0, 0, 0, 0, 0};    
int  circleArray[11][9] = {  {5, 5, 5, 5, 5, 5, 5, 5, 5},
                             {4, 4, 4, 4, 4, 4, 4, 4, 4}, 
                             {4, 3, 3, 3, 3, 3, 3, 3, 4}, 
                             {4, 3, 2, 2, 2, 2, 2, 3, 4}, 
                             {4, 3, 2, 1, 1, 1, 2, 3, 4}, 
                             {4, 3, 2, 1, 0, 1, 2, 3, 4}, 
                             {4, 3, 2, 1, 1, 1, 2, 3, 4}, 
                             {4, 3, 2, 2, 2, 2, 2, 3, 4}, 
                             {4, 3, 3, 3, 3, 3, 3, 3, 4}, 
                             {4, 4, 4, 4, 4, 4, 4, 4, 4}, 
                             {5, 5, 5, 5, 5, 5, 5, 5, 5} };

void circle(uint16_t mode) 
{
  switch (mode)
  {
     case 0:
     c[0] = random(255);
     break; 
     case 1:
     c[0] = incColor;
     incColor++;
     break;
  }
  for (int x = 0; x < 11; x++)
  {
     for (int y = 0; y < 9; y++)
    {
       strip.setPixelColor(x, y, Wheel(c[circleArray[x][y]]));
    } 
  }
  c[5] = c[4];
  c[4] = c[3];
  c[3] = c[2];
  c[2] = c[1];
  c[1] = c[0];

}

into the real life application....

www.famousmods.com for more info

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2 Answers 2

up vote 3 down vote accepted

References may do what you want:

int &circleArray[11][9] = ......

This will make circleArray an array of references rather than copied values.

Edit: above isn't supported by the standard, and support is compiler dependent.

Using pointers instead, you would have

int *circleArray[11][9] = {{&c5, &c5, .....

and then change all the circleArray acceses to be *circleArray[x][y] instead of circleArray[x][y].

A different approach, which may be more versatile, would be to keep colour array indices in circleArray:

int incColor;
int cn[6] = {0,0,0,0,0,0};
int circleArray[11][9] = { {5,5,5,5,5,5,5,5,5},
                           {4,4 .....

Then c0 would become c[0] and you would access the array value like

cn[circleArray[x][y]]

you could also make circleArray uint8_t to save some space, as all entries will fit inside a byte.

share|improve this answer
    
I tried this and *circleArray[11][9] and the error i got was C:\Program Files (x86)\Arduino\hardware\arduino\cores\arduino/Print.h:63: note: size_t Print::print(long unsigned int, int) <near match> –  Hockeyman271 Feb 28 at 1:16
    
If you use *circleArray[11][9] it will achieve a similar thing, but you will need to de-reference the pointer each time you access circleArray as a value, by putting the star out the front. Where was the error when you used &circleArray ? –  sj0h Feb 28 at 1:24
    
Test1:8: error: declaration of 'circleArray' as array of references it wont let me verify the program, it crashes on the declaration of the array –  Hockeyman271 Feb 28 at 1:41
    
Ok, so it seems that arrays of references are not supported by the C++ standard, but some compilers allow them. In that case, you are back to pointers. I'll edit the answer to show the pointer method. –  sj0h Feb 28 at 1:52
1  
doing it that way may also help other code, like your series of assignments at the end can now be done in a for loop, ie for(int i=5;i>0;--i) c[i]=c[i-1]; –  sj0h Feb 28 at 5:34
up vote 0 down vote

circleArray[0][0] won't be the same as c5, because on assignment a value is copied from one variable to another.

To alias one location to multiple variables, you should use pointers or references.

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