implementation of a dynamic 2D array

[rummy98]

I attempted to do this using a pointer to a specific data
type, say int:

int* x;

then i created a single dimension array to hold the columns

x = new * int [10] // this gives me an error for the *
I wouldn't know any other way to create an array of
pointers?!?

then I would use a for loop to traverse the rows:

for (int i = 0; i < 10; i++)
{
x[10] = new int [10];
}

to me, this should create a 10x10 2D array...please find
my error in thinking, this is really frustrating

thanks
rummy

 

[hcexi]

You used bad pointer. Istead of using pointer to pointer to int, you used just pointer to int... Check example:

#include <iostream>

int main()
{
	// you need a pointer to array of (10) pointers :)
	int** array = new int* [10];

	// you need then to allocate memory for (10) arrays
	for ( int i=0; i<10; ++i )
		array[i] = new int[10];

	// do something 
	for ( i=0; i<10; ++i )
	{
		for ( int j=0; j<10; ++j )
		{
			// random value <0,9)
			array[i][j] = ( int ) ( ( rand() / double( RAND_MAX ) ) * 10 );

			// display
			std::cout.width( 3 );
			std::cout << array[i][j] << &quot; &quot;;
		}
		std::cout << std::endl;
	}

	// deallocate (10) arrays
	for ( int j=0; j<10; ++j )
		delete[] array[j];

	// deallocate pointer to (10) arrays
	delete[] array;

	return 0;
}

 

[rummy98]

thanks hcexi, I actually didn't know I could

assign a variable as a pointer pointer (**) ;-P

Also, thanks for the destructor...I prolly

would not have destroyed each individual array

before destroying the initial one....there would

have been hanging pointers everywhere. tks again!

rummy