dynamic memory allocation..

I am an experienced C programmer and i have clear understanding in cpp.. lately i have been having problems with dynamic memory allocation, that too double pointers.. in C, its easy to use, using malloc.. how do i do it in CPP?? (using new not malloc) for example.. char **str; in C i use one malloc to allocate an array of pointers and then use a loop to allocate the individual pointers. how do i do the same in CPP using new operator? i tried doing str = new char[x][y], but it didnt work, it gave me some weird errors (i am using vc++ .net).. please tell me how do i allocate memory using ''new'' in cpp.. thanks in advance..