#include<stdio.h>
#include<stdlib.h>

/*
 * C does not have new and delete
 * instead you use malloc and free, and realloc
 */

/*
 * examples of passing dynamic arrays to functions
 * and manipulating the values
 */

void init ( int ** arr, const int rows, const int cols )
{
    int i,j,k = 0;
    for ( i = 0 ; i < rows ; ++i )
        for ( j = 0 ; j < cols ; ++j )
            arr[i][j] = ++k;
}

void print ( int ** arr, const int rows, const int cols )
{
    int i,j;
    for ( i = 0 ; i < rows ; ++i )
    {
        for ( j = 0 ; j < cols ; ++j )
            printf ( "%3d ", arr[i][j] );
        printf( "\n" );
    }
}

int main()
{
    {
        /* allocate an array of ints */
        int i;
        int size = 10;
        int * arr = ( int * ) malloc ( sizeof ( int ) * size );

        /* use it */
        for ( i = 0 ; i < 10 ; ++i )
            arr[i] = 10 - i;
        for ( i = 0 ; i < 10 ; ++i )
            printf( "%d ", arr[i] );
        printf( "\n" );

        /* growing arrays is easy with realloc */
        size += 10;
        arr = ( int * ) realloc ( arr, sizeof ( int ) * size );
        for ( i = 10 ; i < 20 ; ++i )
            arr[i] = 30 - i;
        for ( i = 0 ; i < 20 ; ++i )
            printf( "%d ", arr[i] );
        printf( "\n" );

        /* free them when you are done */
        free ( arr );
    }

    {
        /* allocate a 2D array of ints */
        int i;
        int rows = 5;
        int cols = 4;
        int ** arr = ( int ** ) malloc ( sizeof ( int * ) * rows );
        for ( i = 0 ; i < rows ; ++i )
            arr[i] = ( int * ) malloc ( sizeof ( int ) * cols );

        /* use it */
        init ( arr, rows, cols );
        print ( arr, rows, cols );

        /* free them when you are done */
        for ( i = 0 ; i < rows ; ++i )
            free( arr[i] );
        free( arr );
    }

    {
        /* another (nicer) way to allocate a 2D array of ints */
        int i;
        int rows = 6;
        int cols = 10;
        int * tmp = ( int * ) malloc ( sizeof ( int ) * rows * cols );
        int ** arr = ( int ** ) malloc ( sizeof ( int * ) * rows );
        for ( i = 0 ; i < rows ; ++i )
            arr[i] = tmp + i * cols ;
        /* use it */
        init ( arr, rows, cols );
        print ( arr, rows, cols );
        /* free them when you are done */
        free( arr );
        free( tmp );
    }

    return 0;
}