Double arrays with pointers

[Guest42]

I have a quick question about the nature of making a 2D array using pointers, as in

int **v;

I tried making a little piece of code like this:

int **twoDee;
int i, j;
twoDee = (int**)malloc(X*Y*sizeof(int));
twoDee[2][1] = 5;
printf("%d", twoDee[2][1]);

This was just so I could try and access twoDee after initializing it and assigning a variable. However, the program crashes before anything is printed there, so I guess I'm unaware of the proper syntax. Can someone show me what it is?

 

[cpjust]

int i
int* pInt;
int** ppInt;

/* Allocate array of 5 ints. */
pInt = malloc( 5 * sizeof( int ) );


/* First allocate array of 5 int* pointers. */
ppInt = malloc( 5 * sizeof( int* ) );

/* Then allocate 5 arrays that are each 5 ints long. */
for ( i = 0; i < 5; ++i )
{
   ppInt[ i ] = malloc( 5 * sizeof( int ) );
}