Question

Can we dynamically allocate 2D array without using any for loop or while loops?
i there any direct command or function in c c++?

Answer 1

Without using a loop you will have one restriction in ISO c++ i.e. size of one dimension has to be determined at compile time. Then this allocation can be done in a single statement as follows:

#define COLUMN_SIZE 10 // this has to be determined at compile time
int main()
{
    int (* arr)[COLUMN_SIZE];
    int rows = 20; // this is dynamic and can be input from user at run time
    arr = new int[rows][COLUMN_SIZE];
    arr[3][4] = 10;
    cout << arr[3][4] << endl;
    return 0;
}

The memory allocated with new needs to be freed. Also if we extend it to n dimensions, only one of these dimensions can be determined at run time. The reason is that compiler has to know the size of each row in order to create a row of contiguous memory.