hello everyone!
i have a quiz about 2D Arrays.
and i don't know how the questions might be,
can you help me :)

thank you.

PS:please correct my grammar mistakes if you see any, i'm here to learn.

thank you

We can help you if you would tell us what you don't understand about 2d arrays.

well i think i do understand that 2D array is to create two spaces in memory one for row and the other for col..

No.. A 2D array will still allocate 1D block of memory.. It's just how you access this.. For example:

    rows = 13;
    cols = 10;
    int* values;
    values = new int[rows*cols];

    for(unsigned i=0; (i < rows); i++)
        for(unsigned j=0; (j < cols); j++)
            values[i*cols+j] = 0.0;

We are still using a 1D block of memory, however, accessing this 1D of memory as a 2D (array).. Does this make sense/

A 2d array is declared like this:

int values[10][20];

It is very similar concept to an Excel spreadsheet, which has columns and rows. In the above declaration the array has 10 rows and 20 columns. What phorce illustrated above is a 1d array, not a 2d array.

thank you so much guys!
it helps.

still waiting an example of 2d array question:(

Here is an example:

A 2D array is initialised and represented as the following:

(type) -> name - > [][]

So as follows:

int 2darray[100][100]

This initialises a value of 100 rows and 100 cols note that in memory it is still a 1D block of data, the compiler, therefore, does not allocate data for rows and cols.

The following can be seen as a 2D array:

int main(int argc, char *argv[]) {

    int vals[100][100]; // 100 rows, 100 cols

    for(unsigned i=0; (i < 100); i++)
        for(unsigned j=0; (j < 100); j++)
            vals[i][j] = 0;


This can also be repesented as a 1D block (example, given above) where the memory is allocated for a 1D block, however, how we access it and therefore read from it changes.

Does this make more sense? Or, is there a specific question on 2D arrays?

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