read array 2 dimensions in another way C++

Question

after reading inputs to an array:

std::vector<unsigned char *> inputs(elements);

the "inputs" is a 2 dimensional array: inputs[3][2], then reading this array out, the values are:

inputs[0][0]=1
inputs[0][1]=2
inputs[1][0]=3
inputs[1][1]=4
inputs[2][0]=5
inputs[2][1]=6

I would like to read this 2-dimensional array into one dimensional array:

int counter=0;
int * allElements = new int[6];

for(int i=0; i<3; i++)
   for(int j=0; j<2; j++)
   {
      allElements[counter++] = (int)inputs[i][j];
   }

That is a traditional way of reading all of the elements into one dimensional array and I believe if I read the elements of "allElements" this way:

for(int i=0; i<6; i++)
   printf("%d ", allElements[i]);

and it should be: 1 2 3 4 5 6

However, I would like to read all elements of two dimensional array into the 1 dimensional array such that when I do it like this:

for(int i=0; i<6; i++)
   printf("%d ", allElements[i]);

It should be: 1 3 5 2 4 6

In the words, reading all of the first elements of 2 dimensional arrays first.

How can I achieve this way?

Why are you using unsigned char * instead of vector<int>? — moshbear
– moshbear, Commented Nov 14, 2011 at 23:42

drdwilcox · Accepted Answer · 2011-11-14 22:28:12Z

2

Just swap your i and j loops.

answered Nov 14, 2011 at 22:28

drdwilcox

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Comments

Edwin de Koning · Accepted Answer · 2011-11-15 07:12:31Z

1

All you need to do is reverse the order of the loops:

int counter=0;
int * allElements = new int[6];

for(int j=0; j<2; j++)
  for(int i=0; i<3; i++)
   {
      allElements[counter++] = (int)inputs[i][j];
   }

That should do the trick.

edited Nov 15, 2011 at 7:12

Edwin de Koning

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answered Nov 14, 2011 at 22:30

mr.tenuki

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Comments

Olle89 · Accepted Answer · 2011-11-14 22:28:41Z

0

for(int i=0; i<3; i++)
   for(int j=0; j<2; j++)
   {
      allElements[counter++] = (int)inputs[j][i];
   }

answered Nov 14, 2011 at 22:28

Olle89

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