CODEWITHSUNDEEP
c++carrays
dobleV
dobleV

Reputation: 307

How do i select the other column in a 2-dimensional array?

How do i select the second column of a 2-dimensional array. I have this array with about 30 values (LKT) and from there I have a 2-dimensional array (ScaledValues). The 2nd column of this 2-dimensional array will be filled with a scaled version of the original LKT array.

Initially, ActiveArray variable points to the LKT array. However, when I populate the 2nd column of the array in ScaledValues with scaled values of the first LKT array, how do I move ActiveArray to now point to the second column as the active array that i'll be using? i.e. After i fill the second column with the desired scale values, I'd like to work with those values and I want to use ActiveArray variable to denote that this new column is the active array.

I know there are other ways to do this i.e. I could create 2 separate individual arrays but I have to use the format that you see below. please assist. thanks.

Please let me know if i need to make my question clearer.

Thank you very much. 

static const unsigned int LKT[30] = {
    30, 29, 28, 27, 26, 25, 24, 23, 22, 
    21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 
    11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};

static unsigned int ScaledValues[30][2];


static volatile unsigned char ActiveArray = 0;

Upvotes: 0

Views: 115

Answers (2)

001
001

Reputation: 13533

Reverse the ScaledValues array declaration:

unsigned int ScaledValues[2][30];

for (int i = 0; i < 30; i++) {
    ScaledValues[0][i] = LKT[i];
    ScaledValues[1][i] = scale(LKT[i]);
}

// Also need to make this a pointer
unsigned int * ActiveArray = ScaledValues[0];    // Original values
ActiveArray = ScaledValues[1];                  // Scaled values

Upvotes: 1

MOHAMED
MOHAMED

Reputation: 43518

the easier way to manipulate this array could be done as following

first the definition should be in this way

static unsigned int ScaledValues[2][30];

then to copy LKT to the first line (and not column)

memcpy(ScaledValues[0], LKT, 30*sizeof(unsigned int));

to access to the second line of the ScaledValues array is

ScaledValues[1]

Upvotes: 0

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