2D Array in C++

There are multiple ways to create 2D arrays in C++.

The important thing to note it there could be below cases:

1. Rows known at compile time but column unknown
2. Rows unknown at compile time but column unknown

• Rows known at compile time but column unknown

int r=3,c;

 int *arr[r];    //Valid configuration

/*

  now from some where we have received no of columns 

      i.e.   c = func();

*/

    for (i=0; i<r; i++) 

         arr[i] = (int *)malloc(c * sizeof(int)); 

• Rows unknown at compile time but column unknown

int **arr;

int c,r;

/*

  now from some where we have received no of columns 

      i.e.   c = func1();  r  = func2();

*/

int **arr = (int **)malloc(r*sizeof(int *));

for(int i=0;i<c;i++){

 arr[i] = (int *)malloc(c*sizeof(c));

}